I'm pretty sure that most, if not all, Cubans who go on to become doctors do...superficially...ask themselves the question you pose, NJ. They probably all come up with the same answers, along the lines of: "I have dreamt of being a doctor since I was eight years old"..."My parents encouraged me in every way to realise that ambition"..."I want to heal people and make the world a better place"...and so forth.
I doubt whether they ever seriously consider becoming street-sweepers. And well done to them, I say!