But your physical form w/r/t a sport isn't really a matter of controversy since no one thinks a 5'7" person is going to become a basketball great, although it's not totally impossible http://en.wikipedia.org/wiki/Spud_Webb

But even in athletics it's more about the type of practice as shown by this study of swimmers: http://www.lillyfellows.org/Portals/0/Chambliss-Mundanity%20...

What I mean is, of course there is "natural talent" in being 6'7" that pushes you towards one sport and away from another, but that's not that interesting I don't think. What's interesting are those things-- chess, music, writing, film making, etc.-- that aren't tied to physical types, and so far the evidence seems to be that talent is largely a myth.

Now, the interesting question you raise is why do some people keep going and others give up.