As a matter of fact, I have 3 boys who have different needs, but are always looking for activity.
My eldest, near 20, goes to the gym with me now. He is heading into the Air Force shortly. Skinny, but wiry and fast.
The next one, 14, has a heart defect, and cannot lift heavy...so he is the champion of sit ups and pull ups. He does alot of dips sometimes also. He's a real show off, and does so during his gym class, destroying all opposition.
The "baby" of the family, 11, loves lifting a 50 lb sandbag, which I keep next to the one I lift. He does other things also, but the sandbag is his favorite. Go figure!
I've wondered aloud for years about why gyms have not created programs for kids, which are actually interesting and fun.
Not all kids are interested in team sports, which is a religion in my area, and that leaves a huge number of kids with nothing physical.
I have some ideas, but I am looking at the ISSA Youth Fitness Trainer program before I implement them.