A very tricky question for me. (Potentially long block of text ahead, you have been warned.)
If you had asked me what I wanted to be when I grow up at, say, eight years old, I would've told you "zoologist" without blinking. Having always been fascinated with nature and animals, it seemed like a logical path to follow. So, at 14 (the age of high school enrollment in my country), I chose a gymnasium; where I live, gymnasiums are general knowledge high schools, as opposed to vocational schools that prepare you for a specific profession, so you essentially have to attend university after them. When I finished high school, I enrolled into a Faculty of sciences where I gained my bachelor, masters and, as of this year, PhD in biology, in addition to working there since 2015.
But. One of the biggest problems I feel we have as a collective society today is that humans are forced to choose careers that should sustain them for a lifetime at an age when they are utterly incapable of making a well rounded, carefully thought through decision. Or, at least, I feel this is true of myself. As time went by, I started to resent my job. Academia and science is absolutely a good career choice for many people, but not for me. I find myself feeling out of place, I am disillusioned by many of the practices of the people around me, and, crucially for my own sense of self worth, I feel like I'm not being useful at all, not contributing to society in any meaningful way. I'm using the job as a means of self preservation and nothing else.
I have drawn and written stories ever since I was a kid, but I am uncertain whether I could ever make it into a full career. The environment I live in sort of considers you... let's say strange if you ever wish to change your career. You're supposed to be thankful that you even have a job and just quietly grin and bear it until retirement: in my experience, rarely do people entertain the idea that, if you don't like your job, you should go ahead and find a new one. But I don't see myself living like that. I don't want to waste my life doing something that brings me no personal fullfillment and gives me no sense of value and contribution. I'm not saying that I can't do it - I just feel my potentials would be better utilized elsewhere.
Where exactly - I haven't a clue. So, I guess the answer to the question asked by the creator of the topic is: I'm still figuring it out. My one goal that I have, and that I would love to achieve, is to publish at least one book in my life. Any book, really - just leave some kind of imprint on the world that means something to me personally.
Sorry for going on for a bit, and sorry if all of this sounds whiny or boring. I just felt like putting it out there, and sharing my two cents.
TL;DR: Haven't a clue, hope to figure it out.