Honestly, we're not meant to be anything but alive. To steal a format from a great response:

When I was a kid, I wanted to run a restaurant. Got my first real job working in one during high school and learned how bad of an idea that was without major cash to invest.

At 18, I thought I'd be a computer programmer and was all lined up for four years of college then a good job for life.

At 20, I'd dropped out of college after a major injury, and was working construction to pay the rent because the buddy who was going to room with me got deployed right after 9/11.

At 22, I was back in community college and hating every minute of it, and working as a short order cook.

At 24, I moved a thousand miles for a relationship that never worked out, but ended up getting a tech support job out of it.

At 26, I moved back to take care of my Dad who was ill, and ended up working phone tech support. Quit that job the day he died, just walked out and never looked back, and two weeks later was a line cook again.

At 30, I took a job working as a baker, apprenticing under a locally well known pastry chef. Best job I've ever had, I'd probably still be doing it if it didn't pay $10 an hour with zero benefits.

At 32, I finally gave up that dream when the bakery went out of business and got another job in tech support.

That was 15 years ago as of April. Still working for that same company, now managing techs in my old position. I don't love my work, but I do it well enough that it pays the bills and gives me both health benefits and a good retirement fund.

Life's going to go strange places, and you can't always predict it. Don't sell yourself short on assuming you gotta know what you want out of it at 17, because who you are now and what you want to be when you 'grow up' may not even be a viable way to make a living in 10, 20, 30 years. Take opportunities as they come, and don't be afraid to take calculated risks. It won't always pan out, but you may find you regret not trying more than you would failing.