Can you be whatever you want to be? Nope. Not gonna lie; you can't.
I will never be a concert pianist. Besides the fact that I'm too old to start now, it will never happen, simply because my pinkies are too short. I can't reach more than 7 notes at a handspan without difficulty.
The point is that finding the right job is at least as much about looking inside, finding what your skills, talents and abilities are, as looking out there.