I have a fun mental exercise I like to run through called “what’s the last thing I’d ever think of.” It falls along the lines of the Zen Kōans (eg: “what is the sound of one hand clapping”), but find it helps me open my mind when I feel like I’m too deep in a project. It’s something I like to do when relaxing on the back porch, or sitting in an airplane like I’m doing now. It’s a fun activity to pass time that obviously can never be completed because you can always find something more obscure than your previous thought.
I used to try to think of the last thing I’d ever think of at the most intense times in school, so even during my high school graduation I tried to force myself to remember something totally far away (time and/or distance), like what the blender at home would be experiencing at that very moment, or little newts my sister and I used to find under rocks in my backyard in Virginia. Even though importantly seeming events are going on around me, or a problem I am thinking of is consuming my every thought, things like blenders at home and amphibians under rocks in back yards in Virginia still exist. Maybe next time you’re stuck on a problem, try to broaden your thoughts to give your brain a chance to relax, then refocus itself on the problem from a different angle.