My office used to be right by the local art museum, and I was a member. Whenever I felt stuck, I'd go take a half hour to look at art, and usually a solution would quickly come to mind.
“I generally liked to work on my more difficult subjects, like math, in the morning, when I was fresh. I still practice this approach today. I have some of my best mental breakthroughs in the bathroom and shower—it’s when I take my mind off the subject that the diffuse mode is able to work its magic.”