Science! If I could wave my hands and live the life I really want, I would become a scientist. To create knowledge that never existed before is an utterly compelling thing to me.
The below sort of sums it up for me. It's from this interview of a sociologist of science, Harry Collins [http://www.scientificamerican.com/article.cfm?id=scientists-know-better-than-you]:
Question from Scientific American: You've spent the past 30 years studying gravitational wave physicists. What do you like about them?
Answer from Harry Collins: They're my ideal kind of academic. They're doing a slightly crazy, almost impossible project, and they're doing it for purely academic reasons with no economic payoff. I consider myself an academic who's made the bargain that I want to have an interesting life, and I'm prepared to have a little less status and a little less money as a result.