How I Chose
When I was in high school, I wanted to be a writer, but when it came time to choose a career path, I decided that it wasn't very smart to major in writing. If I didn't get published right away, how would I make an income? I had always been told that I would make a good teacher, so I decided to combine that with my love of the English language and majored in English Literature and Education, while taking the occasional writing class when I could.
I ended up working part-time in a daycare while I was in college, and, when I didn't get hired as a middle/high school teacher, I ended up as a full-time staff member at the daycare when I graduated. Since I had a degree, they offered me a teaching position, and I taught there for ten years. It was a stressful job and it didn't pay very much, but, for the most part, I enjoyed it. It was never boring!
Just recently (in June), I left that job to pursue writing. Right now, I'm working as a freelance editor and writer while writing on my own and exploring ways to get my writing "out there." It's been kind of a roundabout way of getting here, and I definitely wouldn't say that I've "made it" yet, but I don't regret my choices.
I think that there are a lot of people who don't know what they want to do when they're in high school, and I think that's okay. If you want my advice, here it is:
First, look at your reality. Are you able to take a year or two before you make a decision? If so, there are lots of great opportunities. Get some work experience. Do an internship in a field that interests you. Do volunteer work. Meet people. You might discover more about yourself that will inform your decision.
If you aren't able to take time off, then I would suggest looking at your future in a broader sense. You don't have to know specifics right now. Do you want to go to college? If so, you can go without declaring a major and take some gen-ed courses and see what you like. If you still struggle to find a degree you like, I would recommend going for something more general. A degree in something like Business or Communications can get you in the door almost anywhere.
If you're thinking in terms of school subjects, you might think that there isn't and area that you excel in. Try thinking of it in a broader sense. Are you a highly-organized person? There are lots of administrative jobs out there. Are you a people person? Lots of companies need charming, positive people to be out in front. There's also positions like recruiters (head hunters). If you're on here, you're probably a decent writer. There are all kinds of jobs that involve writing (and not just novels). Think about how you go about doing things and what that says about your skills. You could even ask your family, friends, and teachers how they would describe you to get a better sense of your skills.
There's a lot of pressure on people your age to choose now what you will do for the rest of your life, and once upon a time, that's the way it was done. But these days, it's just not that way anymore. Now, a lot of people switch companies and even entire career paths two or three times before they find the one they want to settle down in. My recommendation is, don't rush it if you don't have to. Give yourself time to get to know yourself outside of high school (because, believe me, you will not be the same person a few years from now!). And don't worry so much about finding the "right" career. Unless you want to go into a career that will take years of schooling before you can even start (like medicine or law), there's nothing that says you can't change your mind in a couple of years. Spend time thinking about it, but try not to stress over it.
Good luck!