The Power of Habit

Charles Duhigg
Rating: 8.2

“Few books become essential manuals for business and living. The Power of Habit is an exception. Charles Duhigg not only explains how habits are formed but how to kick bad ones and hang on to the good.”
-Financial Times

Part One: The Habits of Individuals

Chapter 1: The Habit Loop: How Habits Work

The book begins with the story of Eugene Pauly, a 71-year-old man who lost the medial temporal lobe of his brain to viral encephalitis. The rest of Eugene’s brain remained perfectly intact, and he had no problem remembering anything that occurred prior to 1960 – but suffered from total short-term memory loss, unable to retain the knowledge of any new event for more than a minute and constantly repeating his words and actions from a minute before.

Eugene had no memory of his grandchildren, and couldn’t even tell you where his kitchen or bedroom was located, even when he was sitting in his own home.

However, in an effort to make sure Eugene got some exercise, his wife had begun taking him on a walk around the block each day. She became frantic one day when he disappeared, only to show up 15 minutes later after taking the walk by himself. He couldn’t draw a simple map of his block or even tell you where his house was, but he began taking that same walk around the block every day.

Eugene had demonstrated what scientists had suspected but never before proved: that habits are formed and operate entirely separately from the part of the brain responsible for memory. Later tests confirmed that we learn and make unconscious choices without having to remember anything about the lesson or decision making.

Your brain is constantly seeking new ways to save effort and is always “chunking” sequences of actions into automatic routines. Backing out of the driveway, for example, requires over a dozen separate actions, but many of us do it daily without a second thought.

The habit process consists of a three-step loop:

The Habit Loop

  1. Cue. A trigger that tells your brain to go into automatic mode, and which routine to use.
  2. Routine. Physical, mental, or emotional behavior that follows the cue.
  3. Reward. A positive stimulus that tells your brain that the routine works well, and is worth remembering.

Simply understanding how habits work makes them much easier to control. By learning to observe the cues and rewards, we can change the routines.

“If you believe you can change – if you make it a habit – the change becomes real.”

― Charles Duhigg #thepowerofhabit

Chapter 2: The Craving Brain: How to Create New Habits

It might surprise you to learn that in early 20th America, hardly anyone brushed their teeth; in fact, so many recruits during World War I had rotting teeth that government officials declared poor dental hygiene a national security risk. That all changed, however, when a marketing genius by the name of Claude Hopkins was convinced by an old friend to apply his skills to hawking toothpaste.

Claude was the man responsible for taking unknown products like Goodyear and Quaker Oats and turning them into household names. His signature tactic was to tap into the habit loop by anchoring the product to a specific trigger, regardless of how preposterous the connection. Quaker Oats, for example, owes its success to Claude being able to convince America that it provided 24-hour energy – but only if you ate a bowl every morning.

Claude chose a similar cue to turn toothpaste into a national habit. His ads read, “Just run your tongue across your teeth. You’ll feel a film – that’s what makes your teeth look ‘off-color’ and invites decay.” After giving people the cue, he continued with images of beautiful white smiles and the statement, “Note how many pretty teeth are seen everywhere. Millions are using a new method of teeth cleaning. Why should any woman have dingy film on her teeth? Pepsodent removes the film!”

The claim was downright false; the “film” is a naturally occurring membrane, and toothpaste doesn’t do anything to remove it. However, the cue was universal and easily apparent, and people bought the connection to the reward (beautiful teeth). Within a decade, toothpaste usage had expanded from 7% of the population to 65%.

The author contrasts this success with the abysmal failure of P&G’s Febreze when it first came onto the market. It was a legitimate technological marvel that worked like a charm; the problem was the phenomenon of the human olfactory system that causes people to become used to any smell and lose the ability to detect it. The lady with nine cats and a house odor to the match had no cue sufficient to induce her to use the product that would probably transform her social life.

P&G executives were about to axe the product when the product management team discovered what scientists already knew: that a habit is only formed when the brain begins to anticipate and crave the reward the moment the cue is introduced, before the routine is even completed. You can’t sell a product that provides scentlessness because there is no cue available for the brain to anticipate.

Febreze sales went through the roof once P&G began marketing the product instead as an air freshener – a product to be used as the final step of a cleaning routine to make the room pleasantly aromatic. Once people tried the product, they began to crave the clean smell from that finishing spritz of Febreze. Only later did P&G begin to mention the real value of the product – the breakthrough chemical formula that actually eliminates odors, rather than just cover them up.

It is here that the authors reveal that Claude Hopkins’ techniques really had little impact on the sales of Pepsodent toothpaste. Plenty of other toothpaste companies were using similar techniques long before Pepsodent came along.

In reality, that particular toothpaste’s success was completely accidental. Without foreseeing the impact of the choice, Pepsodent had included citric acid, mint oil, and other ingredients that created that now-familiar cool, tingling effect. That feeling created a cue – people missed the feeling when they forgot to brush their teeth. The tingling serves absolutely no purpose other than to let people know the product is working. (The foam in today’s toothpaste is similarly unnecessary from a functional point of view.)

“Rather, to change a habit, you must keep the old cue, and deliver the old reward, but insert a new routine.”

-Charles Duhigg

Chapter 3: The Golden Rule of Habit Change: Why Transformation Occurs

Tony Dungy changed the game of American football with a counterintuitive coaching approach: instead of trying to outmatch his opponents with thicker playbooks and complex schemes, Tony drilled his team on only a few key plays. He did everything he could to get his team to stop thinking, and react based on habit instead.

Tony knew that habits can’t usually be overcome; instead, a habit can only be changed if a new routine is successfully inserted into the process with the same cue and the same reward. He trained his team to automatically link the cues they already knew to different on-field routines – ones that involved less complexity, fewer choices, and more subconscious reactions. In succession, with this approach, Tony turned two abysmal teams into championship contenders.

Perhaps the most famous and widespread example of successful habit change is the 12-step program of Alcoholics Anonymous. The author is fascinated by how a physical addiction with psychological and genetic roots is frequently conquered by an unscientific, unstructured, and largely arbitrary system that addresses neither the psychiatric or biochemical factors that experts say are the foundation of alcoholism.

The first key is that AA inserts a new routine into the cue/reward sandwich by identifying what needs the alcohol is fulfilling (escape, relaxation, companionship, anxiety relief, etc.) and providing a similar type of relief through the AA group.

However, this alone isn’t sufficient to keep alcoholics (and you and I) from falling off the wagon when the stresses of life boil over beyond a certain point. There is one other crucial element: belief.

While current scientific knowledge of the mechanisms of belief is severely limited, the fact nevertheless remains. Belief is an ingredient and a skill that makes habit change possible and even begins to spill into other areas of life. (See chapter 2 of Think and Grow Rich summary for more on the importance of the nebulous concept of belief.)

Belief in the intervention of a higher power was a common theme in research into AA’s success, but other people likewise play a large role. The author quotes Todd Heatherton, one of the authors of a 2005 UC Berkeley, Brown, and NIH study of the power of AA’s method: “Change occurs among other people. It seems real when we can see it in other people’s eyes.”

“The Golden Rule of Habit Change: You can’t extinguish a bad habit, you can only change it.”

“Change might not be fast and it isn’t always easy. But with time and effort, almost any habit can be reshaped.”

― Charles Duhigg #thepowerofhabit

Part Two: The Habits of Successful Organizations

Chapter 4: Keystone Habits, or The Ballad of Paul O’Neill: Which Habits Matter Most

In October 1987, Paul O’Neill stepped on stage to deliver his first speech to investors as the new CEO of Fortune 500 manufacturer Alcoa. New CEO’s usually followed a fairly standard script about costs and profits, the evils of government interference, and promises to implement various business buzzwords.

Instead, to his audience’s great perplexity, Paul opened with, “I want to talk to you about worker safety.” He expounded on his goal of making Alcoa a zero-injury workplace before proceeding to point out the fire exits in the room and instruct his audience on their use in case of emergency. More than one audience member questioned his sanity.

Paul was immensely successful in his stated safety goals; by his retirement eleven years later, Alcoa went from having about an accident a week at each plant to boasting a worker injury rate that was one-twentieth the national average. More interestingly, however, Alcoa’s income had risen 500%, and its market capitalization had increased by $27 billion.

When O’Neill took the job, Alcoa was criticized for poor quality and a slow workforce. His predecessor tried to mandate quality improvements, and the result was a 15,000-employee strike. Looking back, O’Neill explained, “I knew I had to transform Alcoa, but you can’t order people to change. That’s not how the brain works. So I decided I was going to start by focusing on one thing. If I could start disrupting the habits around one thing, it would spread throughout the entire company.”

He used what the authors call a “keystone habit” – a habit that causes a chain reaction of habit disruption. During his time as a government employee, Paul had learned to recognize how institutional habits governed processes, with suboptimal results.

Paul instituted a better habit loop at Alcoa. Whenever there was an injury (cue), the unit president was required to provide Paul with an injury report, as well as an action plan to ensure that type of injury never happened again, within 24 hours (routine). The promotion was dependent on compliance with this requirement (reward).

For a unit president to meet the 24-hour deadline, he needed to hear about the injury from his VP as soon as it happened. The VP had to be in constant communication with the floor managers, and the floor managers had to rely on the workers for safety suggestions so they would have an answer for the VP when he asked for a plan. As these patterns shifted to meet the safety requirements, other aspects of the company also began to change. Better safety quickly translated into increased quality and efficiency.

There are many other keystone habits in various areas of life that lead to wider shifts in behavior. For example, people who begin an exercise habit typically find that they start naturally eating better, being more productive at work, and feeling less stressed.

“Typically, people who exercise, start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. Exercise is a keystone habit that triggers widespread change.”

-Charles Duhigg

There is a vast chasm, however, between understanding this principle and actually applying it. Identification of a relevant keystone habit requires a trial-and-error approach, with the goal of finding what the authors call a “small win”: a minor advantage that sets into motion patterns that have a much larger impact.

For example, a 2009 weight loss study found one such “small win” when the researchers instructed one group of participants to make no lifestyle changes other than keeping a daily food log about what they ate. The participants naturally began to identify patterns, which made them want to do a better job of planning ahead for their meals, which in turn led to healthier food. The group that kept the food log lost twice as much weight as the other study participants.

Chapter 5: Starbucks and the Habit of Success: When Willpower Becomes Automatic

Scientists have known for many years that willpower is an essential ingredient for success, even more so than intelligence. In one famous Stanford study from the 1960s, researchers sat down four-year-olds at a table with a single marshmallow and told them that they could either eat it immediately or wait until the researcher came back 15 minutes later and earn an extra marshmallow.

The researchers later tracked down the kids when they were in high school, and found that the ones who could maintain their self-control long enough to earn two marshmallows as four-year-olds now had better grades, SAT scores, and social success. (The book The Marshmallow Test is titled based on this experiment, and is a great read itself.)

We also know that we all have a limited supply of willpower. In a Case Western study from the 1990s, researchers instructed a group of undergraduate students to skip a meal, then sat them down together, each one in front of two bowls. One bowl contained fresh, delicious chocolate chip cookies, while the other held somewhat less appetizing radishes. Half were told to eat only the cookies, and the others were told to only eat the radishes. The researchers then gave the students an impossible puzzle to complete.

None of the students knew that the puzzle was impossible, but the students who had just consumed the radishes gave up far sooner than the students who had just eaten the cookies – an average of eight minutes, as compared to 19 minutes of perseverance for the cookie eaters. This 60% disparity was caused by the depletion of the radish eaters’ willpower when they had to resist the cookies. (This is why you don’t want to waste your willpower in the morning on tedious, unimportant tasks like writing emails.)

In addition, numerous studies have shown that by exercising willpower in one area, like exercise or academics, you will increase your reserve of willpower and be able to apply it to other areas of life. However, none of these things are enough to consistently exercise sufficient willpower.

The key is something that has been integral to the success of coffee chain Starbucks: methodical planning of a routine for those inflection points (cues) where pain and temptation are the strongest.

Starbucks’ training systems guide employees through the identification of inflection points (such as when an angry customer is yelling because they got the wrong drink), and matching of the inflection point to one of the company’s dozens of routines. By choosing a certain behavior ahead of time, willpower becomes a habit, and employees are able to provide a high level of service that makes customers keep coming back for expensive lattes.

Another key to Starbucks’ success is the way the company encourages employees to use their own intellect and creativity. In a study at the University of Albany, students were put in front of a tray of cookies.

The researchers nicely asked half the students not to eat the cookies, explained to them the purpose of the experiment, and thanked them for contributing their time. The researchers told the other half not to eat the cookies without explaining the experiment’s purpose or thanking them. In an unrelated standard computerized focus test afterward, the first group significantly outperformed the second.

While scientists may not completely understand the mechanisms of the process yet, it is clear that people perform far better, and have much greater willpower when they feel like what they are doing is a personal choice, and when they understand the purpose. When people are just following orders, willpower becomes much more difficult.

“Willpower isn’t just a skill. It’s a muscle, like the muscles in your arms or legs, and it gets tired as it works harder, so there’s less power left over for other things.”

― Charles Duhigg #thepowerofhabit

Chapter 6: The Power of a Crisis: How Leaders Create Habits Through Accident and Design

The author contends, “There are no organizations without institutional habits. There are only places where they are deliberately designed, and places where they are created without forethought.” All companies have unspoken routines that make it possible to operate; otherwise, firm leaders would never be able to keep up with all the new permutations of decision-making that front-line workers deal with every day. While an organization may think it is making deliberate decisions via formal research and development processes, in reality, dozens of convergent habits, processes, and behaviors are responsible.

If some new colleagues asked you how to succeed at your company, it’s unlikely that you would refer them to the policy handbook. You might educate them instead of the informal rules, truces between company divisions, and lines that should not be crossed. If you work at a successful organization, it is probably because company leaders have cultivated organizational habits that provide a balance of power and keep the peace, but also make it clear who is in charge.

“Companies aren’t families. They’re battlefields in a civil war.”

― Charles Duhigg #thepowerofhabit

In the early 2000s, Rhode Island Hospital was considered to be one of the nation’s leading medical institutions. However, a toxic culture created by arrogant doctors who mistreated nurses and rejected their input led to a series of tragic operating room mistakes, fines, and negative publicity. The hospital became the poster child for medical mistakes, targeted by both local and national media. It was a genuine crisis, and the new Chief Quality Officer used the situation as an opportunity to implement changes that had previously been proposed, but blocked.

Video cameras were installed in operating rooms, checklists were mandated for every surgery, and an anonymous reporting system was implemented. Changes like these, in addition to new training systems that emphasized better teamwork, empowered the nurses to prevent operating mistakes. As a result, the hospital has since earned several prestigious awards for the quality of its care.

Chapter 7: How Target Knows What You Want Before You Do: When Companies Predict (and Manipulate) Habits

As companies have begun to rely more heavily on big data over the past twenty years in order to better predict consumers’ buying habits, they have realized that most purchasing decisions are made the moment a customer sees a product. Despite a shopper’s intentions, habits are often stronger than pre-written grocery lists. From a retailer’s perspective, however, there is a difficult problem: these habits are unique to each person. If you want to take advantage of this knowledge about how people buy products, you can’t use one-size-fits-all sales or marketing techniques.

As a solution, companies like Target have been collecting individualized shopping data for the past decade or so, using credit, loyalty, rewards, and frequent shopper cards. Combined with data that can be easily purchased about your age, marital status, location, ethnicity, and so on, retailers have an incredibly detailed picture of who you are and what is going on in your life.

If you purchase a box of popsicles about once a week around 6:30 on a weekday, as well as mega-sized trash bags each July and October, Target knows that you probably have kids, stop for groceries on your way home from work, and have a lawn that you need to mow in the summer and rake for leaves in the fall. The algorithms will see that you buy cereal but not milk, and calculate that you must be purchasing your milk somewhere else. You’ll then get coupons for milk, school supplies, lawn furniture, and so on, while your single neighbor in an apartment across the street will receive completely different coupons.

Companies that use these advanced data mining techniques also found something else that is absolutely crucial to their marketing success: when people go through major life events, they often change their purchasing habits. As a result, these corporations are extremely interested in identifying when you experience a job change, move, relationship change, or birth of a child – and they are very good at it.

Now, when Target deduces that you’re pregnant, you’ll get coupons for diapers and maternity clothes intentionally sandwiched between unrelated ads for lawn mowers and beer.

Radio stations today use a similar technique to introduce and popularize new songs. Back when OutKast’s tune “Hey Ya!” first aired, it was a complete flop. Music executives loved the song, and their algorithms confirmed their intuition – the data gave the song one of the highest scores ever. When the song was aired, however, nearly a third of listeners would change the station within 30 seconds.

At the time, the music industry was beginning to realize a fundamental truth about how people relate to songs. While most people will tell you something different, they care more about the familiarity of a song than its quality. In the early 2000s, male listeners told industry researchers they hated Celine Dion, but whenever radio stations played Celine Dion songs, they stayed tuned. The areas of the brain that process music naturally hone in on patterns and familiarity. In other words, our musical preferences don’t dictate what we listen to; our subconscious habits do.

With the industry beginning to realize this fact as “Hey Ya!” was released, radio stations recognized that the song was probably failing simply because it was unlike other tunes played in the Top 40. They began to sandwich the song between two other familiar, popular songs – the more bland and unoriginal, the better – cementing OutKast’s track as part of the already existing habit loop in listeners’ minds. “Hey, Ya!” went on to win a Grammy, drive 5.5 million album sales, and earn radio stations millions.

The lesson here is not simply to be suspicious of the industry’s manipulation of your habits; instead, realize that it is a supremely powerful tool to sandwich a new habit you wish to nurture between your already existing routines.

“Small wins are a steady application of a small advantage.”

― Charles Duhigg #thepowerofhabit

Part Three: The Habits of Societies

Chapter 8: Saddleback Church and the Montgomery Bus Boycott: How Movements Happen

At 6:00 on Thursday, December 1, 1955, American hero Rosa Parks uttered her now-famous refusal to give up her seat on the bus. (Contrary to the commonly held belief, she wasn’t even in the “white section,” and there were already three open seats for the white man to choose.) Mrs. Parks wasn’t the pioneer of this act of defiance; in fact, within the past few months, two similar incidents had already occurred. It was Rosa Parks, however, who sparked the civil rights crusade, and as you might have guessed, it was habits that were responsible.

Rosa was deeply involved in her community, belonging to dozens of religious, social, charity, and hobbyist groups that usually didn’t come into contact with each other. It all started when the former head of the Montgomery NAACP and a white lawyer, both friends of Mrs. Parks through her various activities, posted her bail and asked her permission to use the incident to mount a legal challenge to the city’s segregation laws. By the end of the day, news of her arrest had already spread throughout the community (a much more unusual phenomenon in those pre-Twitter days), and an influential schoolteacher’s group had already suggested a boycott on the day of Rosa’s appearance in court four days later.

These various groups immediately printed and began distributing flyers, and within 24 hours, word had spread even further. It wasn’t just the leaders who knew Rosa; hundreds of individual group members considered her a friend. People who only months before patiently endured the gross indignities of a hideously racist legal system and largely ignored similar injustices heaped upon strangers now responded to the call in Mrs. Park’s defense.

It wasn’t that the civil rights hero had thousands of close friends; she simply had what sociologists call “weak ties.” As Malcolm Gladwell discusses in The Tipping Point, weak ties are more important, in many ways, than close friends. For example, they tend to be more valuable in connecting us to jobs, because they connect us to groups and information that we otherwise wouldn’t know. Our close friends usually run in the same groups we do, so they’re unlikely to be able to connect us too much outside of our own sphere.

In the case of the Montgomery bus boycott, weak ties were powerful because they created peer pressure. Most people won’t jump to seriously inconvenience themselves for a loose acquaintance, but Mrs. Park’s web of connections created peer pressure. You risked losing face and social standing in the community if you didn’t participate, just like you or I would lose standing in our social circles if you refused to help out a friend of a friend with a résumé referral. When the town newspaper printed an article about how the black community was planning to boycott the buses, the city took it as social proof that everyone was doing it. The boycott became a new social habit that spilled into larger social habits of peaceful protest, jumpstarting the civil rights movement and eventually leading to the Civil Rights Act of 1964.

Chapter 9: The Neurology of Free Will: Are We Responsible for Our Habits?

In 2010, a cognitive neuroscience researcher discovered something fascinating when he used an MRI machine to compare the brains of pathological gamblers against merely social gamblers. When they watched slots roll on a video screen, there was some difference in how excited the pathological gamblers’ brains were when a winning match displayed. More interestingly, however, the social gamblers correctly registered the near misses as losses, while pathological gamblers registered them as wins.

This is a crucial difference in the habit loop. After the cue of the near-miss, the pathological gambler’s mind provides a reward, creating a habit loop that leads to more gambling. The same cue in a social gambler’s mind only leads to a reward when he or she stops gambling and escapes the loss of money. This subtle difference in habit loop is responsible for the gambling industry’s profitability, and the ruining of countless lives.

The author questions the morality of holding pathological gamblers responsible for their actions but comes to the conclusion that no matter how strong a habit is, as long as you are aware the habit exists you have the ability to decide to change it. He recounts a story told by author David Foster Wallance. “There are these two young fish swimming along and they happen to meet an older fish swimming the other way, who nods at them and says, ‘Morning, boys. How’s the water?’” The young fish swim on for a bit before one finally asks the other what “water” is. Like the fish, many of us live our lives swimming through a world permeated with habits without even realizing it.


A Reader’s Guide to Using These Ideas

The Power of Habit is perhaps unique among books in that its appendix is the best chapter. Now that you realize you’ve been immersed in habits your whole life, you can begin to shape them to your will. There are infinite habits and thousands of formulas for changing them, but you can find what you need by following this formula:

  1. Identify the routine: Though it’s not always obvious, the easiest part is usually identifying the behavior you want to change.
  2. Experiment with rewards: You can then fill in the “routine” part of the habit loop, but to pinpoint the cue you first have to experiment with rewards. Try out a new reward each time you feel the urge to complete the routine. For example, if you find yourself eating junk food every afternoon, try eating an apple instead, or drinking some coffee, or chatting with a friend for a few minutes. Then set a 15-minute timer, and when it goes off ask yourself if you are still feeling the same urge. If you are, you haven’t yet identified the cue. Keep experimenting, and you’ll eventually figure out if you were actually hungry (in which case the apple would work), if you were tired (in which case the coffee should help), or if you just needed a break (which your friend should provide).
  3. Isolate the cue: Once you’ve determined the reward that satisfies the cue, there is still work to be done to understand exactly what the cue is. Most habitual cues will fall into five categories:
    • Location
    • Time
    • Emotional state
    • Other people
    • An immediately preceding action

If you have a habit you’re serious about changing, keep a log of your location, the time, your emotional state, the people around you, and the action you take immediately prior to your habit. After a few repetitions, you’ll probably be able to see the pattern.

  • Have a plan: Once you’ve recognized the precise routine, reward, and cue, it should be easy to design a different routine that provides the same reward after the same cue. Stay alert for the cue (or set an automatic alert if it’s time-based), and act out your pre-planned routine. If it works, you’ve confirmed that you found the right cue and reward, and your habit will then be easily moldable.


It was a revelation to me that habits dictate nearly everything I do, and after reading The Power of Habit, I realized that success in personal growth and in most endeavors of life is completely dependent on my ability to identify, reshape, and build my habits. Aristotle is credited with the quote, “We are what we repeatedly do. Excellence, then, is not an act, but a habit.”

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