I have a vague recollection of a scientist sharing a problem solving strategy. The content of that quote or strategy, which I do not recollect literally, can be summarized as:
Keep a list of 10 unsolved problems (that you would like to solve) in your head, and every time a mathematician/physicist comes up with a new solution to some problem, take that solution and try to see if you can apply it to any of the problems in the list.
I think it was Robbert Dijkgraaf telling that Robert Oppenheimer said something to this extent, but I cannot seem to find the quote or fragment.
Does anyone know who gave this quote or strategy?