By default I am a physics student, which in the midst of his university-live decidet it would be more effectiv to go chase all the questions that pops up in his own mind, no matter how far they were away from the stuff that the current course required. Every answered question would be one piece of a puzzle, and it would be totally ok to never get the complete picture, as long as there were all pieces together that I decided were important to me. How I decide that? I don't know, it seems to be a strange mixture of how important the puzzle-piece is to my current lectures, and the aesthetics of the questions that the puzzle-piece deals with. And a bit of obsession. Or courese.
When I'm not a physics student (that is because I might be distracted by something) I'm either a musician (check out hurdy gurdys. Do it!), or a guy baking his own bread, or somebody wasting time on the internet.