I wanted to be an astronaut or a paleontologist. The combination of seeing the planets from space and being able to float sounded awesome. Also, I was into dinosaurs at the time.
I gave up the paleontologist thing when I found out that all you get to do is dig fossils and you don't get to meet real ones like Jurassic Park.
And I gave up the astronaut part when I learned you have to be really smart; but also because that one space shuttle exploded and I was like "um... nevermind".