I think it is a wonderful idea and I believe Amy's concern could be covered by verification from the organization or receipt. I also like what Allie is saying since many activities can increase lung capacity and create physical health. I would like the definition of "activities" to include organized sports (soccer, volleyball, basketball, swimming, track ect), dance, Qigong (studies demonstrate increases lung capacity), yoga and other body work, and outdoorsmanship (hiking, biking, skiing, ect).
We are fortunate to live in a city where we have a huge recreation center and what is called the MetroParks (huge preserved park system). They offer many discounted classes and we take ice skating for $20 for 1 hour classes (unheard of). However, it would be neat to have a non-profit cover the expense of joining -- the family membership is $300/annually which is hard for some families I'm sure.
Best of luck to you...keep massaging the idea and get some great non-profit people on your side to start it up and get your funding.
Warmly,