I know I'm late to the party and I'm no longer a teenager, but... I always wanted to work on Wall Street. I worked my ass off in school, keeping a job to be able to afford college. Fortunately I got a full scholarship to attend an Ivy League university, again worked my ass off to graduate with a MSc in Finance. I was recruited by one of the major investment banks... and after spending 6 months there I realised I was working my whole life towards something that made me miserable. Environment was really toxic, all work acquaintances were very superficial and I really did not have any time to spend the money I was earning. By a pure accident I decided to try to my luck in Silicon Valley... and I love it. I never realised that I could find balance between a source of income and something I really enjoy doing.
Long story short OP; the thing you want right now is probably not something you will want to do later in your life. My advice would be: explore, search, try.
If you want to be a US history or Political Science college professor - GO FOR IT! Work hard, focus on and if you decide that's not something you want to do, don't worry.