I was reading an old Economist, seeing as it won't be making it into my stuffed suitcases when I move. There was an article about the intersection of economics and flow. Flow is the deep satisfaction people get from losing themselves in their work, or as W.H Auden put it: "forgetting themselves in a function." Flow is supposed to be easiest to achieve when you are in work that stretches you without defeating you, that provides clear goals, that has unambiguous feedback, and a sense of control.
Which is why I had a strange love of making up new homework lists. Annoying, often a waste of my time as so few students seemed to ever do their damn homework, and yet they were mildly satisfying. That said, can't say I am sad that I will never have to write up such crap again!