Chris Castig Co-founder of Adjunct Prof at Columbia University Business School.

The Power of Habit by Charles Duhigg | Summary and Quotes

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The Power of Habit explains why habits exist, and how to change them. Early in the book the author Charles Duhigg introduces you to the concept of the Habit Loop — a three step process for how habits work. Throughout the book Duhigg uses the Habit Loop as a framework for thinking about changing habits. The following are my book notes and summary from The Power of Habit.

What is The Power of Habit’s “Habit Loop”?

The concept of The Habit Loop is one of the main takeaways from The Power of Habit.

"The Habit Loop" from The Power of Habit

The process of forming a new habit is a three-step loop:

  1. Cue – a trigger that tells you brain to go into automatic mode and which habit to use
  2. Routine – which can be a physical or mental emotion. Ie. you do something each time you are triggered by the cue.
  3. Reward  – the thing you get from doing the habit. This helps your brain figure out if this particular loop is worth remembering for the future. [19]

A few examples of The Habit Loop:

"The Habit Loop" from The Power of Habit

"The Habit Loop" from The Power of Habit

Who is the author?

Charles Duhigg. He’s a Pulitzer Prize–winning reporter at The New York Times,  where he writes for the business section. You can follow him on Twitter @cduhigg.

The Power of Habit Vocabulary

Habit – a decision you made at some point. And then stopped making, but continue acting upon.

Chunking – The process in which the brain converts a sequence of actions into an automatic routines. It’s at the route of how habits form. [17]

Keystone habit – Certain types of habits that lead to a cascade of other actions because of them. For example, when you drink it may also cause you to smoke and overeat. Drinking in this scenario would be an example of a keystone habit triggering other habits. Keystone habits are powerful, because if uncovered they can help cause radical change in your routines.

How to Change Habits

There’s not one Habit changing formula that exists. The book tells us that, “Giving up cigarettes is different from overeating, which is different from changing how you communicate with your spouse, which is different from how you prioritize tasks at work.” 

BUT! There is a Framework for understanding how habits work, which can help you experiment. It’s a place to start.

The Four Steps to Habit Change: 

  1. Identify the routine – Are you eating too many cookies? Are you smoking? Do you want to go to the gym more? Identify which routine you want to focus on.
  2. Experiment with rewards – Isolate what reward you are actually craving. Take a minute and write down a few possible rewards: Does the cookie satisfy hunger? Does it make you more relaxed? Do you need an upper because you’re tired?
  3. Isolate the cue – Ask yourself, what is the trigger for this routine? Charles Duhigg explains that there are five main categories for triggers: location, time, emotional state, other people, and immediately preceding action. Find yours.
  4. Have a plan – Now that you have a hypothesis for what might be your cue, routine and reward, you can experiment. Write out a plan for how you can tackle this. For example: “At 3:30, everyday, I will walk to a friend’s desk and talk for 10 minutes.” Write it down. Stick to it. For how long? According to Charles there’s not a magic bullet for the amount of time (some habits are harder to break/create than others, but at least give it a few weeks).

That’s Charles’s method for breaking his cookie habit. And if you want more there’s 10 pages about the framework in the book The Power of Habit.

The habit loop in action:  

Keep the cue, and provide yourself with a new routine!


Building a habit of drinking more water with the framework

This year, I tried creating a habit of water drinking for myself. One of the hardest things for me at first was counting how much water I was consuming. It’s easy to say “Drink more water”,  but how much is “more”.

Here’s how I used to habit framework.

  • For the cue: a carried around a red bottle with me that counted how many bottles I was drinking, I also setup an additional cue, I used IFTTT to send me a 2pm text message reminding me to drink water
  • Routine: drinking water
  • And for the reward: An index card next to my bed asking me, “Did you drink 4 bottles of water today?” (So in a way, the reward was not feeling shame, and a sense of relief that I hit my goal. For me that worked, although it might not be as strong a reward for everyone.)

During the process I experimented with other cues. Like having an accountability partner: we’d text each other at the end of the day to ensure that we both drank four bottles. This worked for a while, but as soon as one of us went on vacation, or dipped out, we got lazy.

The conclusion, by experimenting over four months I was able to find the right degree of cue and reward to make drinking more water a habit.

I wrote more about my water habit in this post:  Send Yourself a Daily Text Reminder to Drink Water

Notable Quotes

“All our life, is but a mass of habits” William James in 1892 [xv]

On research of habits coming out of Duke University: 

Most of the choices we make each day may feel like the products of well-considered decision making, but they’re not. [xv]

40% of the actions people performed each day weren’t actual decisions, but habits. [xvi]

On habit formation: 

When a habit emerges, the brain stops fully participating in decision making. [20]

The problem is that your brain can’t tell the difference between bad and good habits, and so if you have a bad one, it’s always lurking there, waiting for the right cues.

Habits merge without our permission. [26]

On forming habits with a group 
Belief is easier when it occurs within a community. [89]

Learn more now:

Further Reading:


  • Taylor Bense’s Knife + Joanna Newsom Remix
  • Hey Ya!, by Outcast
  • “Push”, by Birdstar


Title: The Power of Habit: Why We Do What We Do in Life and Business
Author: Charles Duhigg
Hardcover: 371 pages
Publisher: Random House Trade Paperbacks (January 7, 2014)

Buy The Power of Habit on Amazon
Listen to The Power of Habit on Audible (free trial)

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Chris Castig Co-founder of Adjunct Prof at Columbia University Business School.