It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.
“The greatest gift is the passion for reading. It is cheap, it consoles, it distracts, it excites, it gives you knowledge of the world and experience of a wide kind. It is a moral illumination.”
“As I walk'd by myself, I talk'd to myself, And myself replied to me; And the questions myself then put to myself, With their answers I give to thee.”