Habit building products can change our behavior by tapping into the habit cycle of cues, routines, and rewards. The habit cycle works when a cue triggers an automatic routine that leads to a rewarding outcome. Negative emotions are also powerful internal cues. Successful products create variable rewards and require some initial investment of effort to generate future cues and continue the cycle. Products aim to form habits by clearly defining the cue, routine, and reward so that the behavior becomes automatic over time.