Intervention to Increase Physical Activity in Older Adults Using Citizen-science and Modern Technology

"The intervention is comprised of 5 steps:~1. Goal setting: Over a step-counter (smartphone app) participants learn about their daily average step count. They are coached to set individual goals~2. Fitness assessment: To recommend suitable frequency and intensity of walking program using mapped trails~3. Structured walking groups: Promoted and communicated via app. Participants can additionally organize walking groups of their own.~4. Feedback: Participants will see individual and group data over the step-counter app, and they can communicate with others via a communication app. They will be incentivized to reach goals through a gamification approach.~5. Invite friends: After 12 weeks, participants are encouraged to invite people who fulfil the inclusion criteria to join the project"