Framework for designing products that reliably change behavior. Based on a fundamental truth: behavior is not about willpower or motivation—it is a design problem with a predictable equation.

The Fogg Behavior Model = B=MAP. Behavior happens when Motivation, Ability, and a Prompt converge at the same moment.

            HIGH ┃
                 ┃   ★ Behavior happens
                 ┃  (above the Action Line)
                 ┃
  Motivation     ┃━━━━━━━━━━━━━━━━━━━━━━━ ← Action Line
                 ┃
                 ┃   ✗ Behavior fails
                 ┃  (below the Action Line)
            LOW  ┃
                 ┗━━━━━━━━━━━━━━━━━━━━━━━━━
                 HARD                    EASY
                        Ability

The Action Line: When motivation and ability are sufficient, a prompt causes the behavior. Below the line, no prompt works. The line curves: high motivation compensates for low ability, and high ability compensates for low motivation. The reliable strategy is to make behaviors easier (move right), not to pump up motivation (move up).

Goal: 10/10. When reviewing or creating product behavior design, rate them 0-10 based on adherence to the principles below. A 10/10 means full alignment with all guidelines; lower scores indicate gaps to address. Always provide the current score and specific improvements needed to reach 10/10.

Core concept: Motivation is the energy for action. It has three core motivators, each with two sides: Sensation (pleasure/pain), Anticipation (hope/fear), and Belonging (acceptance/rejection). Motivation is powerful but unreliable — it fluctuates like waves.

Why it works: Motivation explains why people want to act, but it is the least reliable element in behavior design. It spikes (New Year's resolutions, product launches) and crashes (day 3, week 2). Products that depend on high motivation fail when the wave recedes. The best designs work even when motivation is at a trough.

Ethical boundary: Never manufacture false hope or exploit fear to inflate motivation. Motivation tactics should connect users to genuine outcomes, not create anxiety that drives compulsive usage.

See: references/motivation-waves.md for deep dive on the three motivators, motivation waves, and designing for troughs.

Core concept: Ability is the capacity to do the behavior. It is a function of the scarcest resource across six factors — the Ability Chain. If any single link is too weak (too expensive, too time-consuming, too confusing), the behavior breaks. Simplicity is not a single dimension — it is always relative to the person and context.

Why it works: Making behaviors easier is the most reliable strategy in behavior design. Unlike motivation, ability can be systematically engineered. Every field you remove, every step you eliminate, every default you set moves the behavior to the right on the Fogg Behavior Model, crossing the Action Line even at low motivation. The Ability Chain provides a diagnostic: find the weakest link and fix it.

Ethical boundary: Reducing friction should make genuinely valuable behaviors easier. Never reduce friction on harmful actions (e.g., making it too easy to overspend, over-share, or delete important data without confirmation).

See: references/ability-chain.md for the six factors in detail, friction audit templates, and simplification strategies.

Core concept: The prompt is the call to action — the thing that says "do it now." Without a prompt, behavior doesn't happen regardless of motivation and ability. Three types: Person Prompts (internal reminders), Context Prompts (environmental cues), and Action Prompts (designed triggers from the product).

Why it works: Prompts are the most overlooked element. Many product teams assume that if motivation and ability are present, behavior will happen. It won't — not without a well-timed prompt. The key insight: prompts only work above the Action Line. Sending a push notification to someone who lacks ability or motivation is spam. The best prompts arrive when motivation and ability are already sufficient.

Ethical boundary: Respect prompt fatigue and user preferences. Every prompt should pass the test: "Would I appreciate receiving this right now?" Never use prompts to manipulate through anxiety or manufactured urgency.

See: references/prompt-design.md for prompt types, timing strategies, notification design, and anchor moments.

The Tiny Habits method is the practical application of B=MAP: make behaviors so small they require almost no motivation, anchor them to existing routines, and celebrate immediately.

After I [ANCHOR MOMENT], I will [TINY BEHAVIOR], then I [CELEBRATION].

Anchor Moment: An existing routine that reliably happens (opening an app, finishing a meeting, morning coffee).

Tiny Behavior: The smallest version of the target behavior — so small it's almost impossible to skip. Not "write a report" but "open the report template." Not "review analytics" but "glance at one metric."

Celebration: An immediate positive emotion after doing the behavior. Celebration wires the habit. Without it, repetition alone isn't enough — you need the feeling of success.

Every target behavior has a Starter Step — the tiniest meaningful version:

Once the tiny behavior is wired, it naturally grows:

The key: never force scaling. Let motivation and momentum drive expansion. The tiny version is not a failure — it is the foundation.

See: references/tiny-habits.md for the full Tiny Habits recipe, celebration techniques, and scaling patterns.

Fogg's systematic process for creating lasting behavior change:

What outcome does the user want? Not the product's goal — the user's aspiration.

List all possible behaviors that could achieve the aspiration. Be exhaustive — don't commit to one behavior yet.

For each behavior, assess: Does the user have enough motivation? Is it easy enough? Use the Focus Mapping technique — plot behaviors on a 2×2 of impact vs. feasibility.

Take the best-matched behavior and shrink it to its Starter Step. Design the prompt. Add celebration.

Once the tiny behavior is wired, expand it. Fix bottlenecks using the Ability Chain. Refine prompts based on timing data.

The Action Line is the visual threshold in the Fogg Behavior Model. Above it, behaviors happen when prompted. Below it, they don't.

Two reliable strategies:

Map B=MAP to product metrics:

This skill is based on the behavior design research developed by BJ Fogg. For the complete methodology, research, and case studies:

BJ Fogg, PhD is the founder of the Behavior Design Lab at Stanford University, where he has directed research on behavior change since 1998. He created the Fogg Behavior Model (B=MAT/B=MAP), which has become the foundational framework used by product designers, health researchers, and behavior change professionals worldwide. Fogg coined the term "behavior design" and has trained thousands of innovators in his methods, including the founders of Instagram (Mike Krieger was a student). His research on "captology" (computers as persuasive technology) created an entirely new academic discipline. Tiny Habits distills two decades of research into a practical system for behavior change, demonstrating that lasting change comes not from motivation or willpower but from designing behaviors to be tiny, anchored, and celebrated. Fogg's methods have been adopted by product teams at companies from Silicon Valley startups to Fortune 500 enterprises, and his academic work has been cited over 20,000 times.