Establish hooks to provide value and help people form healthy habits. The Hook Model:. External Trigger. Action. Variable Reward. Investment. Internal Trigger. Predictable rewards aren't intriguing. Email, links, app icon. Behavior done in anticipation of a reward. User puts something into the product: time, data, effort, social capital, money. Improves the experience for the next go-around. Inviting friends, stating preferences, building virtual assets, learning to use new features. Build products to help people do the things they already want to do, but for the lack of a solution, don't do. Technology can enhance lives to improve relationships, make us smarter, and increase productivity. Connect the user's problem to a solution frequently enough to form a habit. Hooked users become brand evangelists.