One of the best things I ever heard about learning jiu-jitsu was a reminder of how much jiu-jitsu I'd never get to know. There's something of that spirit in this personal essay by black belt Stephan Kesting:
The Real Secret to Mastering a Skill
In the popular new age Ophrah conception of the world the only thing stopping you is your imagination or – alternately – your lack of belief in yourself.
We tell our kids, “Honey, you can be anything you want to be. You just have to believe in yourself…”
We give each other calendars with motivational sayings like, “Conceive, Believe, Achieve.”
Well belief might be important, but it’s not the only thing you need. It’s necessary but not sufficient; those syrupy sayings don’t tell you the whole truth…
The truth is that you CAN be anything you want to be, but only if you’re willing to make the sacrifices that are required.
Anything worth achieving is going to require some kind of sacrifice.