When it comes to live, how do you choose to focus on one thing over another? (choose a path)

EDIT: I meant "when it comes to life" wtf was I thinking????

My life has been a roller coaster for the past few years or so. I went from studying physics to learning programming to design to writing novels and god-knows-where. And I feel like I keep going and I feel like I want to learn and explore everything but I know there isn't time for that. One can't live hundreds of lifetimes (unless you're Hindu).

So my questions are,

• how do you choose between ten different passions/interests you have to pursue one?
• How do you choose to dedicate yourself to something and what drives these choices and your reasoning?

For example, I started programming for money and learned to love it greatly. I was always discouraged from it as a kid (sounds weird, I know) but I took it on myself to learn it and made it into a career for myself. My reasons to go for it were: enjoyment, cash (lots of it), ease, and overall interest.

The thing is, I have ten other interests I'd like to enjoy full time: writing (I've one novel down, would love to finish my second one), concept art (not that great, but I have potential), 3d modeling, cooking, be involved in a sport (heavily), learn Zen so to speak, and so much more. I obviously don't have time to invest years into each immediately. I've also noticed that by not committing myself fully to something, I don't do as well. And sometimes, I find myself in a "so much to do, fuck everything" mood where I just end up not enjoying any of my favorite interests and passions.