My first assistant-coaching job in football was at William & Mary in 1961. The pay wasn't much, so to get $300 more per year, I agreed to coach the golf team. I didn't even know how to keep score, and really, my main job was not to wreck the van on the way to tournaments.
Had I been a great athlete, I'm not sure I would have even gone into coaching. I may have turned out feeling that my life ended when my athletic career ended, as happens so many times with various athletes.