I think part of why I don't think of myself as a jock is because I enjoy certain physical activities but don't have a strong drive to Get Better at them.

I mean, I can see that distinction, but I think my definition is that any sort of dedication to physical activity is what makes you a jock, regardless of how hard you push yourself past that. But I don't know, maybe I just don't know how not to push myself once I've started dedicating myself to something