I've been building a wellness app for my own family, and most of the work has been removing things.
Every app I tried to get my parents onto assumes you already exercise. My grandfather is not going to open that. So a lot of decisions went the other way from the obvious:
No streaks. A broken streak makes people quit and the person I'm building for will break it in week two, then never come back.
No leaderboards. The moment my mother sees she's behind her son, she stops. Comparison motivates the people who were already fine.