I usually switch into a different task. That tends to work pretty well, and doesn't leave me feel like I'm not making progress. When I'm completely stumped or

I usually switch into a different task. That tends to work pretty well, and doesn't leave me feel like I'm not making progress. When I'm completely stumped or frustrated with something, I'll shut everything off for a while. I just go do something. Enjoy dinner, watch TV, play games, hang out with people. Zero thoughts about the problem. Most of the time, re-approaching after a cold boot like that tends to change my perspective so much that I will typically solve the problem with much less effort than I expected would be required. Sometimes this is just caused by being tired when initially approaching a problem and then conquering it after resting. Sometimes I'll suddenly have a realization subconsciously and I'll realize I figured out a solution to the problem without thinking about it. This has worked for me since college. Getting one of those nasty algebra or functional analysis problems and being stuck, then realizing in the middle of playing a game later that you suddenly know how to solve the problem is a great feeling. It's like you're doing work without doing work.