You like him, so that is not motivational enough. He might give it to a charity and let you know that, which would definitely defeat the intent.
More motivational would be to burn a $10 bill of yours every time you don't go to the gym. If that idea horrifies you, then it is a very good motivator, no?
I am in fear of sounding like a broken proselytizing record, but this app is a gismo and nothing more. One has to be ready and willing to change one's lifestyle and nothing short. The app is nice (if it works) but is nothing without the underlying lifestyle commitment.