Why Do You Do What You Do?

I vaguely remember when I was five – I wanted to be a bus driver. It was one of those passing fancies. I don't remember if it was driving the big vehicle around the town or picking up and dropping off all the people, but that was what I wanted to do. For at least a week.

There were random other thoughts between that time and when I started thinking seriously about The Future. When do we think we're old enough to decide what we really want to do For A Living? And why do we think we have to...