Developing Dynamic Theories for Behavior Change

HeartSteps is a smartphone based mHealth intervention that contains the following intervention components: (1) contextually-tailored suggestions for activity; (2) motivational messages aimed at keeping individuals motivated to be active; (3) planning of the next week's activity; and (4) adaptive weekly activity goals. Activity suggestions provide individuals with suggestions for how they can be active, and are tailored based on time of day, user's location, day of the week (weekend/weekday), and weather. Motivational messages are delivered to individuals via a push notification. Activity planning asks users to create a plan of how they will be active in the coming week. Participants are prompted to plan once a week. Each week, as part of the weekly planning, HeartSteps suggests an activity goal for the coming week based on their activity levels the previous week. Participants can edit the suggested goal, and the system-suggested goals top out at 150 minutes of activity per week.