Behavior Change Part 1: Theory

tl;dr I’ve been doing some thinking and research on behavior change and wanted to share what I’ve learned. This is the first post in a three part series on behavior change, covering theory, case studies, and how to build products for behavior change.


Behavior change is one of the highest leverage ways to improving human health. If we eat better, exercise more, and become less stressed, we would be happier in the short term, healthier in the long term, and save an enormous amount of burden and cost for the healthcare system. It seems like a no-brainer, and yet many of us struggle to keep good habits. It’s simple but hard.

I’m an optimist and believe that everyone has great potential to be the best version of themselves. We’ve all seen examples of people who lost 50+ pounds and are now living their best lives. We get inspired reading Why We Sleep or Atomic Habits, and are ready to start our personal transformation. This can work, and I hope you’ve been successful in your own behavior change.

Unfortunately, most of the time that positive change doesn’t stick. Our brains are a thin layer of executive function wrapped around a reptilian brain, and most of the time we’re just trying to feel more good and less bad and reproduce, either directly or indirectly. Short-term gratification is usually misaligned with longer term success, and it’s it’s always so easy to give into temptations.

People in the medical establishment are generally pessimistic about behavior change. We’ve yet to prove what the “magic formula” might be to realize behavior change at scale. Some good results have been shown by the likes of Omada, Livongo, Iora, and others, but it’s generally very operationally complex and high marginal cost to deliver. Doctors and medical researchers aren’t experts in building great consumer products, so the polish and functionality is often lacking. And, perhaps most importantly, there are limited monetization pathways for such innovations, and companies working on these products either need to climb a mountain to convince employers or value-based payers to fork over the cash, or convince consumers to pay their own hard-earned cash.

Let’s contrast this situation with pharma, and it’s clear why they’re able to capture so much more of healthcare spend:

  1. There are clear validation pathways with clinical trials.

  2. Medications work at scale (all that’s needed is to take a pill).

  3. Medications have low marginal costs (“just” mass production and distribution).

  4. Patents allow the extraction of significant profits from each approved medication.

  5. Drugs clearly fit into a fee-for-service reimbursement scheme.

Setting aside the question of who pays, I’d like to focus instead on whether significant behavior change to improve health outcomes is possible at scale. This series represents my best attempt at answering this question, with a heavy emphasis on understanding the state of the art.


Many have written about behavior change, and to stand on the shoulders of giants it’s worth quickly going through some best practices from the literature. Here are some high-level summaries of core concepts and ideas. And yes, these are mostly pop-sci books that at best approximate literature, but this should at least provide us with some high-level direction.

Most of these focus on habit formation. Habits provide compound interest for personal development, and are a crucial component of behavior change.

Tiny Habits, BJ Fogg

BJ Fogg is a prominent Stanford professor who researches “Behavior Design” and wrote Tiny Habits. He advises breaking down lofty goals into small, specific habits, which can be done automatically and minimize the need to constantly stay motivated. Don’t aspire to be stronger, aspire to do 1 pushup per day, establish that small habit, and build from there. He also has an elegant model of behavior change:

B=behavior, M=motivation, A=ability, and P=prompts. More here.

In this model, you need a prompt in order to initiate an action, but the prompt will only be successful if the action is above the “Action Line”. If you have low motivation and low ability, it will fail, but with high motivation and high ability, it will succeed. Also, with more ability, less motivation is required.

Hooked: How to Build Habit-Forming Products, Nir Eyal

This book considers how we can apply the science of behavior change to consumer products. We see a familiar loop of Trigger, Action, and Reward, with the additional component of Investment. As you repeatedly take action within a product, you continue to provide data, improve your network, and personalize your experience, and this provides both a richer experience, and more psychological attachment to the product itself.

Eyal advocates looking at each of these components separately. Make the triggers loud and obvious, increase motivation and ability, and provide variable rewards to maximize the amount of dopamine produced by a given action. Pay close attention to the connection between the trigger and outcome, and make the loop as tight as possible.


Nudge, Richard Thaler


Thaler won a Nobel Prize for his work establishing that humans don’t make decisions as rationally as economists previously thought. Humans are guided by impulsivity, emotions, and strong personal preferences. We can “nudge” people to make better choices by accommodating and designing for these irrational behaviors. People might underestimate the risk of a heart attack because they don’t know anyone who had one, even if their risk is high. When people are exposed to temptations, it’s easy to act against your long-term goals, for example eating more of something than you want because your plate is larger, or accepting a cigarette when offered even though you want to quit. We can be nudged by our environment towards better behaviors by putting fruit at eye level and junk food out of sight. Defaults are extremely powerful; many more people will become organ donors just by making it opt-out rather than opt-in.

This book is an important reminder that rational reasoning isn’t as motivating as emotion, and that it’s important to shape your environment to help you towards your goals, rather than relying on motivation.

The Power of Habit, Charles Duhigg


All habits have the same three components:

  1. Cue: The trigger that tells your brain to initiate the habit

  2. Routine: The action to actually perform the habit

  3. Reward: This provides feedback to your brain to reinforce this pathway and do more of it in the future

Habits are powerful because your brain will automatically perform the action - the cue pushes the first domino, and the rest fall deterministically. They can be used for good or bad, so it’s up to you to understand how they’re formed and broken to shape your life accordingly. To form a new habit, focus on having a simple cue and a clear reward; when your brain starts expecting the reward upon exposure to the cue, the habit will be formed and automatic. To change a habit, you can keep the cue and reward fixed, but insert a new routine, for example, if you’re tired at the end of the day, talk to a friend instead of reaching for a glass of wine.

He identifies “keystone habits” as a critical piece for personal transformation. Once you’re running every day, you can use that for motivation to eat better, drink less, etc., and you can even stack new habits to use the end of a habit as a cue.

Atomic Habits, James Clear


Clear’s central message is that small actions lead to big results, because habits provide compound interest on self-improvement. If you get 1% better per day, after a year you will have improved 37x, while 1% worse will leave you at almost 0.

He builds on Duhigg’s work with a simple four-step process for new habit formation, which provides a clear framework for creating a good habit or breaking a bad one:

He also emphasizes the importance of environment, and that habits can be easier to form in a new place, free of your existing associations and behaviors. Also, if you want to break bad habits, rely on shaping your environment rather than your motivation, which comes and goes and is an unreliable partner.

You can stack your habits so each habit provides a subsequent cue. You can “bundle” your habits by pairing something you don’t really want to do with something you do, like watching your favorite reality show while working out at the gym.

Community is important; we’re social creatures and naturally want to fit the norms of a group that we’re in. You’ll build better habits by joining a group that embodies your desired behavior. 

Reframing your activities can be helpful. Think about going for a run as an opportunity to build endurance rather than saying “I need to go run”. Also, think about your behavior change in three layers: identity, process, and outcomes. Try to reframe your identity as “someone who moves every day” rather than simply wanting to lose weight. Then, prove this new identity to yourself with consistent small wins, and you’ll start to shape your worldview in a direction that’s empowering and makes things stick.

He also focuses on making habits specific, small (e.g. less than two minutes), and obvious. It’s hard to meditate for 20 minutes, but anyone can meditate for one minute. And to initiate the habit, don’t say “I’ll do it in the evening”, make it tangible, “After I pour my cup of coffee each morning.” Ignore the size of the habit; once you’ve established a habit, then you can worry about optimizing and increasing the difficulty. Fall in love with the process, make sure you’re putting in the time, and if you miss a day, make sure you don’t miss two. Before you know it, the compounding will kick in and you’ll be making tons of progress.

Cognitive Behavioral Therapy (CBT)

CBT is one of the most effective and validated psychological approaches to address problems from depression and anxiety to substance abuse and beyond. It often shows similar or greater efficacy than pharmaceutical approaches, and can be delivered by a therapist or a chatbot (e.g. Woebot). It focuses on values, attitudes, and beliefs about a problem, and by changing how we think, it can change how we act. You’ll see this approach underpinning many services that are focused on behavior change.

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