Solving research problems is hard. After a while I feel mentally spent. I want to be as productive as possible but I don't know of many good ways to "recharge my batteries" after I have been thinking hard.
I have tried taking walks but in the winter it is snowy and cold outside. I have tried socializing with my colleagues but I find it hard to focus when I get back to work. I have tried switching to easier tasks (like email) but that doesn't seem to recharge my energy levels much.
What are some good ways to take a break so that I can come back to my work refreshed, energetic and enthusiastic?