I have a ritual that I do daily, almost without thinking about it anymore. As I am walking to or from the time clock at work, I take a deep breath (sometimes closing my eyes, sometimes not) and work on trying to relax and release some of the stress that I am physically holding in my body. I try to relax my overly tight muscles, correct my posture so that my body is more open, and moves more freely, and let go of all the things that are bearing down on me after a long shift. (I do this other times too, but this is the most regular.)
That deep, cleansing breath is the first and most important step of the whole process. Sometimes, even just stopping to just breathe is the most important thing you can do to release stress and tension from your body, and free your mind to focus on finding a solution. Breathe deeply and get oxygen flowing to your brain and to your rebelling, clenched muscles. Find a tiny moment of mindfulness to be fully in the moment, not worrying over the next thing you have to do, and the next, and the 50 things after that. Just breathe in and breathe out, slowly and deeply.