Really interesting, but I don't know if it is all 100% sustainable. As I read in the yahoo article:
"When you sync your band to the Fitcoin app and start your workout, itll automatically begin recording the length of your activity and the level of your heart rate.
The algorithm within the app then triangulates those stats to determine how much energy youre expending, and ultimately, how much thats worth in Bitcoin."
https://www.yahoo.com/tech/this-app-pays-you-in-bitcoin-based-on-the-113689371979.htmlI didn't try the app, but I think it is a very "successful" applied idea.