The greatest truths are the simplest. I believe the answer to this question is to do more and try more while you're still young.

Honestly, from what I've observed, you don't. It finds you. Life is funny that way. I think that what people should do is to learn about and try out a lot of different things, to maximize the odds of it finding you.

You have to find/choose your purpose, but never the work. Work should come to you.