Most of us want to practice the things we’re already good at, and avoid the things we suck at. We stay average or intermediate amateurs forever.

and

And if the neuroscientists are right, you can create new brain cells—by learning (and not being stuck in a dull cubicle)—at virtually any age. Think about it… if you’re 30 today, if you take up the guitar tomorrow, you’ll have been playing for TWENTY years by the time you’re 50. You’ll be kicking some serious guitar butt.

From How to be an expert by Kathy Sierra