Very nice advice from Feynman. It is always something I also try to live by. If you enjoy working on something, then it's worthwhile. But for me, a lot of times

Very nice advice from Feynman. It is always something I also try to live by. If you enjoy working on something, then it's worthwhile. But for me, a lot of times this may mean working beyond my field, as my interests are varied. I also enjoy problems that cross the boundaries of different disciplines.