I don't think working out is a necessary condition for success, unless you're so unhealthy as to be physically incapable of doing the things that you need to do in order to be successful.
But the kind self-control you need for fitness could also help you become successful. If so, there might indeed be some correlation between fitness and success.
From personal experience strictly: First and foremost the exercise is something we can all use, successful or not. What working out did help me do is get into a sort of a discipline and made me eat and drink proper healthy food. A side effect of workout, indeed a good one for all us chair-dwellers, is that it fixed my posture as well - no wrist pain, no back pain, no neck pain ...
One of the fittest guys I know, works out and runs several miles every morning, has terrible wrist pain. I know 3 other similar people at my current job.
I don't think your lack of pain has anything to do with your working out. More likely luck, genetics, or lack of other activities that would lead to pain.
But the kind self-control you need for fitness could also help you become successful. If so, there might indeed be some correlation between fitness and success.