Practise.
Okay, not particulalry startling, but this here research (and by research I mean magazine article) also suggests that, to truly master something, there is a certain number of hours of practise you need to get under your belt, and it doesn't matter whether you wnat to be a virtuoso on the violin or an evil criminal druglord, it's the same figure.
10,000 hours.
That's about 10 years, if you're dedicated, and appears to be the amount of time people thought of as the foremost practitioners in their field have spent getting to the top of their game. So I was thinking, what could I become a master of in ten years if I started in earnest now. I recently carved a hallowe'en courgette, which shows promise, although it's not as scary as might be anticipated:

Imagine how awesome that would be if I'd been doing nowt else for a decade! Makes you wonder, doesn't it?
So, what would you do, if you had the time and support? Ten years from now, you too could be an expert courgette carver, although I think the planet is too small for more than one.
Get your own niche.