While doing some study-related research, I stumbled upon a nice article on doing what one loves by Paul Graham:
Although I might disagree with one or two particular things, I think Graham has some excellent points. Especially his musings on people's motivations sound really familiar and accurate. They reminded me of Terry Pratchett's words: "Too many people want to have written." Luckily the hacker culture probably isn't as tempting as writing novels, and "Too many people want to have written killer apps" isn't excruciatingly true. At least, not yet.
P.S. If someone has read Graham's book Hackers & Painters, let me know what you think about it.