1. There's a man in my town who has small hands yet plays the guitar fast and well. His secret? Extra large frets so that he doesn't have to use much pressure.
2. Doc Watson probably plays pieces in just the right key and tunes his strings to fit the piece. His instruments are probably custom made to fit his hands and body and are probably in perfect repair. If he makes a noticeable mistake in recording, he does it again or a technician fixes it. So don't beat yourself up if you can't do what he does.
3. Professional musicians don't have to beat up their hands and wrists the way the rest of us do. Just one example - pulling weeds is very hard on tbe hands and wrists. I have to do it, or the city would be after me, but I doubt if Doc Watson does.