If he’s in high school try to get him into competitive sports. I coached HS baseball for three season, so I’m partial. But involvement in any such sport at that age can be very formative for later life, and odds show his chances of future success - even in this barryworld - are better overall.
Best of success to Him and to You.
We had a kid on our team who was fat and slow running. But he could hit fairly decent and, man, could he block a base path-- a natural for catcher. His slowness on the base paths turned out to be not such a big deal because he would either clear them with an extra base hit or strike out most of the time.
I was a skinny little runt and couldn't hit well, but I did learn to throw well enough that I made a fairly decent relief pitcher and to field well enough to be a utility infielder. I also learned how to get on base a lot by walks . . . just by being patient at the plate and learning most kids at the jr. high/high school level couldn't throw strikes most of the time.
I still keep in touch with much of the old gang from way back then even though I've lost track of almost all of my graduate school class.