As a small kid, I wanted to build stuff (didn't really know the title for it back then). Much to the frustration of my surroundings, as everything was a potential building material and everything was subjected to being hammered, nailed, screwed, glued, taped and stapled together... *ahem*
As a teenager, I wanted to study biology and biochemistry, both of which was my passion in highschool.
As a young man, I wanted to be a programmer and so, for good and for ill, I started on my current carreer path.
I guess I have driven it as far as I can in my current line of work (technical manager in a software development company), so the "what do you want to be" question is a bit hard to answer. Perhaps I might want to go full circle some day, assuming I make enough money to retire early, go back and start studying biology and biochemistry again >_