I really have no idea how people can know these things, and make decisions like that. I'm 41 and I still have no clue what I ought to do for a career.
At the risk of boring everyone to death, here's my story of trying to decide what I want to "be when I grow up."
I joined the Air Force straight after high school, because I had no idea how to make it on my own, or what people actually "do". Looking at a university catalog, with all the different majors, I had no clue what I might like, because I didn't know what any of it was.
The Air Force was a nightmare, and I basically spent the next 6 years in a deep depression. Why six whole years? Because I hated my job so much, I agreed to give them an extra two years of my life if I could retrain into a different career field. I thought the problem was the job, rather than myself. So I retrained into a field that is so unbelievably wrong for me, that it's astounding. Inflight Refueling Specialist. I breezed through all the academic stuff, and then proceeded to puke my way through flight school. I can't believe that I even attempted such a thing. I hate airplanes, hate the miltary, hate flying, hate the Top Gun wannabe jocks in that social circle...and there was much of the job that I couldn't physically do because I'm WEAK and SHORT. So I told them I wanted to go back to my old field (the desk job that I had hated). They made me pee into a cup to prove that I wasn't on drugs, because only a druggy would not want to fly. I went back to my old job (not at the old place).
When I got out, I had no marketable skills and still no idea what people "do." So I worked at a pizza place and lived with my mom for a while. Then, while watching crappy daytime TV (the true sign of a loser), I saw an ad for a school where you can get an associates degree in electronics and computer technology. I had no idea if I'd be good at it or interested in it, but I needed to do something. I took the entrance exam and blew them all away with my perfect score. I got top marks throughout the course. Later, I would get a job in the field, and was utterly lost and confused, because it was a completely different environment and I didn't know what to do or how to act. I was eventually laid off, but not before meeting my future husband there.
I enjoyed my experience at Heald (the school), though, so I thought I'd go for a BS in computer science, mostly so I could be a full time student and not have to spend as much time at work. I found that although I enjoy math and computer science a bit, I am soooooooo slow at it, that I did poorly in my classes. I could tell that I'd go nuts writing computer programs.
But as part of the general education requirements, I took a linguistics class. I loved it! This one was offered by the English department, but the other available linguistics classes where anthropology classes. So I changed my major to cultural anthropology. WTF? Another example of me having no clue what I like. Those linguistic classes were duller than watching paint dry, and the rest of the course was just as bad. But I graduated, after many years. During my time there, I met zero people. I would have graduated with a 4.0, if it wasn't for all those math/computer science classes...and one particular class where the professor didn't explain what she wanted properly, so I got a C.
Now I'm a mom, and me staying home with the kids is working out well. But it doesn't pay, and I'm not earning anything towards retirement.