A Simple Equation to Start or Break Any Habit

Every behavior comes down to three variables

BJ Fogg
Published in
5 min readJan 1, 2020


Photo: Deby Suchaeri/Getty Images

YYou can change your life by changing your behaviors. You know that. But as I’ve found in my research as the founder and director of Stanford’s Behavior Design Lab — and as most of us know firsthand — there is a painful gap between what people want and what they actually do.

It took me 10 years of researching human behavior to realize that, when it comes to changing habits, the problem usually isn’t our lack of motivation or discipline. It’s our approach to change. It’s a design flaw, not a personal one.

Every behavior comes down to three variables: motivation, ability, and prompt. Motivation is your desire to do the behavior. Ability is your capacity to do the behavior. And prompt is your cue to do the behavior.

In my work, I group these three things together under the acronym MAP. A behavior (B) happens when the three elements of MAP come together at the same moment: B=MAP.

There are some nuances to the equation. First, motivation and ability have a compensatory relationship: The more motivated you are to do a behavior, the more likely you are to do the behavior. The harder a behavior is to do — that is, the lower your ability — the less likely you are to do it. In this sense, motivation and ability can work together like teammates. If one is weak, the other needs to be strong to get you to follow through.

Secondly, no behavior happens without a prompt. If you don’t have a prompt, your levels of motivation and ability don’t matter. Either you are prompted to act or you’re not. No prompt, no behavior.

Once you’ve learned B=MAP, you can apply it in many practical ways, including stopping or troubleshooting a habit that’s getting in your way. Every month or so, I host Behavior Design Boot Camp, a two-day workshop where I help businesspeople design new systems for various areas of their lives. I ask attendees to tell me about one positive habit they created without much effort, and one “bad” habit they want to stop. At one of my events, a talented executive named Katie nailed how different two behaviors can seem.

Katie’s “good” habit was tied to her productivity. She had a rock-solid habit of tidying…



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BJ Fogg

Stanford behavior scientist & innovator.