I love this!

I was trying to think of a way that if someone signed up to train with me they would have the opportunity to earn a portion of their fee back if they meet some objective metrics. (Weight, waist circumference, 1.5 mile run test)

Funds would be held in either a multi-sig or time lock or something else that I'm not aware of.

When I asked people that were more technical than me they brought up issues like who's going to be doing the verifying, how do you know they're not going to be paid off, blah blah blah, so I sort of dropped it but I'm open to suggestions if you have any.