🧠 The Stanford Professor Who Built Instagram
In 2007, BJ Fogg taught a Stanford course called “Facebook Apps.” The assignment was simple: build something that changes behavior. Two of his students that semester? Mike Krieger, who went on to co-found Instagram. And Tristan Harris, who founded the Center for Humane Technology.
Fogg didn’t teach code. He taught a model so simple it almost sounds trivial: Behavior = Motivation × Ability × Prompt.
Three things need to happen at the same moment for a person to do anything. Miss one, and nothing happens. No matter how motivated you are.
Fogg calls it the FBM — the Fogg Behavior Model. And it changed how Silicon Valley thinks about habit formation.
🤔 The Counterintuitive Trick: Don’t Increase Motivation
Here’s where it gets weird. When a behavior isn’t happening, most designers (and most people) try to increase motivation. “I need to want it more.” “The user needs a bigger reason.”
Fogg says: wrong direction.
Motivation is unreliable. It peaks and crashes. That’s why “New Year’s resolutions” fail by February — motivation is at its highest on January 1st, but ability hasn’t changed at all.
The real lever is ability. Make the behavior so stupidly easy that motivation barely matters.
That’s the “Tiny Habits” method. Want to start flossing? Don’t aim for a full routine. Just floss ONE tooth. That’s it. One tooth takes no motivation, no willpower. And once you’re holding the floss for one tooth, you’ll probably do the rest anyway.
The behavior happens not because you want it more, but because the bar to start is invisible.
🔗 Why Your Apps Won’t Let Go
This is the engine behind every habit-forming product you use.
Instagram’s infinite scroll: no effort, perfect prompt (pull down → new content). Duolingo’s 5-minute lessons: absurdly low ability requirement. The red notification dot on your phone: a prompt so effective you’ll check it even when you know it’s nothing.
For a personal AI companion — every time a user opens the app for a “quick peek” at their daily reading, that’s Fogg’s model at work. The question isn’t “how do I make them want it more?” It’s “how do I make it so easy they can’t not open it?”
Fogg’s students built Instagram’s hook. Tristan Harris later realized the same model could be used against human autonomy — and founded a movement to fight it. Same model, two completely different outcomes.
🎲 The One-Tooth Challenge
Try this today: pick a tiny habit you’ve been putting off. Not “meditate for 20 minutes.” Not “exercise for an hour.” Something so small it’s embarrassing to even call it a habit.
Open the meditation app. Put on your shoes. Write one sentence in your journal.
Fogg’s rule: celebrate immediately after. A fist pump. A “hell yeah.” Your brain needs dopamine to wire the loop. The celebration is not optional — it’s the mechanism.
You’ll probably keep going after one sentence. But even if you don’t — you did the one thing. And tomorrow, one thing again. That’s how Instagram started. That’s how any habit starts.
One tooth.