This Simple Equation Reveals How Habits Shape Your Health, Happiness, and Wealth-Nir&Far
11 Dec 2025 · 7 min
Podcast episode (Near & Far) hosted by Nir Eyal featuring a guest post by James Clear that interprets Kurt Lewin's 1936 equation B = f(P, E) (behavior is a function of the person in their environment). The episode explains that habits arise from both personal characteristics (mindsets, deliberate practice) and environment (physical arrangement, choice architecture, digital triggers), and offers practical tactics (designing for laziness, rearranging cues, simplifying digital inputs) to make good habits easier and bad habits harder. The episode closes with attribution to Lewin (1936) and James Clear (guest author).
Questions this episode answers
1936 (in Kurt Lewin's book Principles of Topological Psychology).
Chapters
Hi, I'm Nir Eyal and this is the near and Far Podcast. This podcast is about business, behavior and the brain. On this show, I do a few things. I read quick articles I've written about topics shaping your behavior. I interview authors of books I enjoy, and from time to time I devote episodes to answering your questions. If you want to ask me a question, visit the podcast page on itunes, go to Ratings and Reviews and ask me a question by leaving a review. I promise to read it and possibly include your question in a future episode. So please ask me anything now. Enjoy the episode and for more, you can always Visit me@nearandfar.com.
This simple equation reveals how habits shape your health, happiness, and wealth by nearandfar.com.
This guest post is by James Clear. James writes@jamesclear.com where he shares ideas for mastering personal habits. Join his free newsletter In 1936, a man named Kurt Lewin wrote a simple equation that changed the way we think about habits and human behavior. The equation makes the following Behavior is a function of the person in their environment. Known today as Lewin's Equation, this tiny expression contains most of what you need to know about building good habits, breaking bad ones, and making progress in your life. Life let's talk about what we can learn from Lewin's equation and how to apply these ideas to master the habits that shape your health, happiness, and wealth. What drives our Behavior? Before Lewin's equation became famous, most experts believed that a person's habits and actions were a result of the type of person they were, not the environment they were in at the time. You can still find many examples of this belief today. For instance, if you struggle to stick to a diet, you might say, I just don't have any willpower. Or if you can't seem to finish that big project, like writing a book, you might say, I'm a great starter, but a lousy finisher. These statements imply that our habits and actions are determined by some set of characteristics that we are born with, that our habits are fixed based on who we are. Lewin, however, said something different. He said that it is not just your personal characteristics, but also your environment that drives your behavior. Your habits are highly dependent upon context. In many cases, your environment will drive your behavior even more than your personality. So maybe you're struggling to stick to that diet because you're surrounded by bad options or unhealthy people, not because you were born with too little willpower. Let's break down these two personality and environment, and talk about how you can improve them to break bad habits and build good ones. The Elements of Personality the first factor in Lewin's equation is the person. We know more about our personal characteristics today than we did when Lewin was around. Perhaps more importantly, we know that your abilities are not fixed in stone. You can improve. The key, however, is to believe you can improve. Carol Dweck, a Stanford professor, has become well known for her work analyzing the differences between the fixed mindset and the growth mindset. When you are using a fixed mindset, you believe that your abilities in a particular area are fixed. When you are using a growth mindset, you believe that you can improve, learn, and build upon your current abilities. While reading Dweck's best selling book Mindset, I found it interesting that the same person can have a growth mindset in one area and a fixed mindset in another. In other words, your identity and beliefs play a role in your habits, and if you're looking to create a new identity, you have to cast a vote for that identity. The best way to improve your abilities and skills is through deliberate practice. The Elements of Environment the second factor in Lewin's equation Environment can often seem like something that happens to us rather than something we have control over. It can be difficult to change where you work, who you're surrounded by, and where you live. That said, there are actually quite a few strategies that you can use to adjust your environment and build better habits. First, you can do what BJ Fogg calls designing for laziness. Fogg wanted to reduce the amount of popcorn he ate. So he took the bag of popcorn out of his kitchen, climbed the ladder in his garage, and put the popcorn on the highest shelf. If he really wanted popcorn, he could always go to the garage, get the ladder, and climb up to get it. But his default decision when he was feeling lazy would be to make a better choice. By designing his environment for laziness, Fogg made it easier to stick with healthier habits. Second, the physical space you live in and the arrangement of the things you come across can dramatically alter your behavior. For example, in his book Nudge, Richard Thaler talks about how grocery store products on shelves at eye level get purchased more than those down by the floor. Researchers Eric Johnson and Daniel Goldstein conducted a study that revealed dramatic differences in organ donation rates based simply on two different types of forms that were passed out. Finally, Massachusetts General Hospital in Boston discovered that they could instantly increase the amount of water people drank and decrease the amount of soda they drank simply by rearranging the way the drinks were displayed in the cafeteria. This concept, which is known as choice architecture, refers to your ability to structure the physical space around you to prime good decisions. Third, we have the digital environment. There are a wide range of digital triggers that prompt our behavior. As Nir Eyal describes, when Facebook notifies you of a new action, you are prompted to log back on. When someone emails you, you are prompted to respond. These digital triggers are simple ways of building habit forming behaviors in online products and services. In many cases, these digital triggers become distractions that take you away from the work and habits that are actually important to you as much as possible. I prefer to combat this distraction by simplifying and eliminating everything that isn't necessary. Another option is to use a service like Freedom to reduce procrastination and distraction Behavior the Person and the Environment Changing your behavior and sticking to new habits can be hard, no doubt about it. Thankfully, Lewin's equation keeps things simple. B F of PE behavior is a function of the person in their environment. Improve yourself and adjust your environment to make good habits easier and bad habits harder. If you can do those two things, sticking with better habits will be much easier.
1 Lewin's equation was originally published in Kurt Lewin's 1936 book, Principles of Topological Psychology. Thanks to Nir for telling me about Lewin's Equation, which led me down the path to this article. This guest post was written by James Clear, who writes@jamesclear.com.
Thanks for listening to this episode of the near and Far Podcast. You can always find more at my blog, nearandfar.com and don't forget, if you have a question you'd like me to explore in a future episode, leave me your question. The former review or the podcast on itunes.