For some of us, the point of almost any endeavor in life is to be “good” at them. That isn’t even to say you can’t enjoy it, or you have to feel anxious about whether you’re good enough at it. The point is the go through the process of becoming good at the things you choose to do because we acknowledge that there is something beautiful and admirable about expertise.
Someone who feels dejected — because he can’t see the reason in doing something unless he’s already hit the requisite hours to be ‘good’ at it — probably needs to hear that he needs to unlearn whatever makes him feel bad about being ‘bad’ at the start, instead of hearing that it’s okay to suck at something as long as he enjoys it.
Otherwise, all you’re doing is trading one form of anxiety for another (I must be good at X vs. I must feel good about X), and he’s still going to notice that he sucks at the thing (playing guitar, golfing, whatever) and find difficulty enjoying it from there.