I usually walk around the neighborhood. And just a few days ago I found out that it could be profitable! Read about the STEPN app. It literally pays for walking and running. You can earn like $20-$40 for a 20-30 minute walk. But there is a tricky part: first you need to purchase virtual sneakers. Anyway, this seems interesting.

I remember the first attempt of doing such an app here on bitcointalk, it was called MangoCoinz:

https://bitcointalk.org/index.php?topic=902788.0