We get better by practicing. An average lifespan provides some twenty thousand days without infirmity. So every day you miss, you’ve lowered the ceiling on your peak skill level.
Injuries and illness take days away from you. A healthy paranoia can reduce those. (So can an unhealthy paranoia; do I really need to put my arm in front of my mouth every time I step off a curb?) Naturally, you’ll need your friends and family to stay healthy as well.
Of course, the quality of practice matters. Staying at peak mental and physical condition takes time away from practicing, but it’s essential. So are vacations.
You also need exposure to other players—playing in groups, taking lessons, attending performances. And to really understand art, to have something to say and be able to say it eloquently, you need education and worldly experience.
Personally I’ve decided the world is a huge and complex place, and it would be sad to look back on life to see only one thing. You’ll notice that I’m not playing first chair for the Chicago Symphony.