The Power of Habit

Why we do what we do, and how to change.

A picture I took last weekend in London

The Power of Habit by Charles Duhigg is a really fascinating read. It offers a wealth of insights on the concept of habits: what they are, why they shape our lives and how we can change them. My goal for this post is to share what I have learned from it. I hope it’ll be helpful to you — both to learn something new and to decide whether the book is worth a read.

First of all, why should you bother? You should if:

  • You have been trying to start a new habit but it just doesn’t stick
  • You want to stop a bad habit but keep failing eventually
  • You’re curious about the psychological processes behind habits

If that sounds interesting, let’s get started!

There are way too many concepts in the book to be listed in this post. Here we’ll just go through the main ideas, and the ones that resonated the most with me. At the end, I have left a list of things that I consider important but could not talk about for lack of space.

Why do Habits exist?

Habits are one way our brain saves energy. They basically allow our minds to go in autopilot mode. They are what happens under the hood when you are thinking about your upcoming presentation whilst brushing your teeth. The “brushing your teeth” action is going on autopilot, without any conscious effort on your side. Attention and working memory are very limited resources. That’s why the brain tries to delegate most of the stimuli responses to the subconscious.

Willpower is limited as well. It’s akin to a muscle: if you exhaust it too early on tedious tasks like checking your email or filling out boring insurance forms, all the strength will be gone by the time you get to the meaty stuff. Treating willpower as a muscle is one of the lessons that impacted me the most from this book. I started doing the most demanding tasks in the morning leaving everything else for later. After only a week, I could already notice a big change in my productivity.

Another related lesson: when people are asked to do something that takes self-control, if they think they are doing it for personal reasons it’s much less demanding. If they feel like they have no autonomy, i.e. they’re just following orders, their willpower gets tired much faster.

How do Habits work? The Habit loop

Example of a habit loop, taken from

The habit loop has three main components: cue, routine, and reward. To show how they fit together, I will use an example from the book: in the afternoon, at around 3:30pm, the author often goes to the local cafeteria to eat a cookie and chat with friends.

The cue is what triggers behaviour. In this scenario it could be a multitude of things: a sense of hunger, the need for a break or the urgency for gossiping with friends. The routine is the behaviour itself, in this case eating the cookie and chatting. The reward is what you get for executing the routine. Here it could be a sense of satisfaction for the sugar in your blood or for the entertaining chatter. Every time the brain receives rewards it strengthens the corresponding loop, in terms of changes in neurological structures. That’s why habits grow incrementally: every time the loop is repeated, the neurological connections linked to that particular craving are grown stronger. With time, the brain begins to expect and crave the reward as soon as the cue arises. This is one of the most powerful ideas in the book: habits are incredibly hard to extinguish. What we can do though is change the routine corresponding to the cue and reward.

Keystone Habits

Keystone habits are those habits whose change is able to spark a shift in other areas as well. As an example, a while ago I used to be a smoker and a heavy coffee drinker. After quitting smoking, in no more than a couple of weeks I also reduced my coffee intake by 80% at least, all without any major effort! What I discovered is that very often the reason for taking coffee wasn’t really the coffee, but improving the taste of the next cigarette. That’s why it was so easy to reduce coffee. Smoking was a keystone habit for me.

The book greatly exemplify this idea in the Alcoa example. Alcoa is the biggest global aluminium supplier, and there was a point in its history where things were not going well. They hired Paul H. O’Neill (former US Secretary of the Treasury) as the new CEO to turn things around. Surprisingly though, he didn’t focus on sales, quarterly earnings or making shareholders happy. Basically all the things you would expect from a CEO. Instead, he decided that worker safety was the priority number one of his new role. It didn’t seem to make sense at first, but quarter after quarter the company’s sales started to increase, while its market value rose from $3 billion in 1986 to $27.53 billion in 2000. The key to understand this huge success is that bad worker safety really was the result of bad habits that were deeply ingrained in the organisation. The changes made in this area were thus able to spread across all aspects of the company’s culture, resulting in the enormous success it had had during that period.

A related concept also exposed in the book is that good leaders seize crises to remake organisational habits. Good leaders know the valuable opportunities behind crises, so much that sometimes they even prolong them, or better, create a perception of them, on purpose. The point is that leaders can’t just order people to change. Instead, great leaders look out for moments of crisis, or even create a sense of it, to push forward the idea that things must change. That is what helps remaking the patterns through which the company lives and breathes.

The Habits of societies: the power of weak ties

The last part of the book is about societal habits: how social movements get started, spread and inspire action. The idea is presented through the example of the civil rights movements, going through the bus boycott movement sparked by Rosa Parks’s arrest. The book argues that one of the main reasons Rosa Parks’s events started a global movement is the power of weak ties. Weak ties are acquaintances: somewhere in between friends and strangers. Your close friends are most likely in the same circles as we are, have the same interests and thus do not provide a lot of new information. Acquaintances, however, are much more likely to know people we don’t know, to provide a different perspective and in general bring new information in our lives.

According to the book, a movement is born through the power of strong ties, is grown through the social pressure generated by weak ties, and becomes self-sustaining when leaders set new habits and these habits become the status quo.

Main Takeaways

To conclude, these are the main takeaways from the book:

  • Habits shape the way individuals, organisations and societies function.
  • Habits exist for a reason: they help us save energy during routine tasks.
  • The habit loop explains what habits are: events that trigger the craving for a reward that trigger a certain behaviour aimed at obtaining that reward.
  • Bad habits can be changed by keeping the cue and the reward and changing the corresponding routine. It’s not easy though: it requires a conscious and continued effort.
  • If you are in a leadership position, where you have the power to shape organisational habits, you can have a huge impact in the way the organisation is run.

Other ideas

This is a non comprehensive list of other notions I couldn’t expand upon in this post:

  • In the appendix, the author proposes a framework for changing habits. One thing to acknowledge is that habits are very different in nature, and there is no one-size-fits-all solution. The framework though can be very helpful in guiding the change. I’m already using it and it is giving good results. It consists of four parts: identify the routine, experiment with rewards, isolate the cue, have a plan.
  • People that plan ahead for setbacks have a higher chance of keeping away bad behaviours. This is greatly shown in the example of the Scottish physical rehabilitation hospital. Patients that were writing their plans in case something went wrong were much more likely to actually take action to mitigate the problem. The point being that no one can eliminate failure, so planning ahead makes you more likely to deal with setbacks.
  • The story of the song “Hey ya” by “Outkast” is a great example of how people like familiar things. The song was deemed too novel and didn’t initially succeed on radios. After some time of playing it along with already familiar songs, it became a huge hit. Which means: if you are to succeed you need to wrap the new things in old clothes.
  • There is one chapter on free will that questions, through the examples of gambling and sleepwalking, whether people do actually have free will or they are just slaves of their habits. The argument made is that you do have control, and the first step in achieving it is believing that you can.




Software engineer, diver, surfer. Mostly writing about programming, data science, and my love for the ocean. Also addicted to Bob Dylan and coffee.

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Gabriele Angeletti

Gabriele Angeletti

Software engineer, diver, surfer. Mostly writing about programming, data science, and my love for the ocean. Also addicted to Bob Dylan and coffee.

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