If I could sum up the best way to clear my head, it would be a nice walk. Well a walk anyway. I just got back from another one. I generally take one a day Tuesdays/Thursdays because I work the afternoons. Mondays, Wednesdays and Fridays might bring one or two or more depending on my mood, the weather and whether T wants to take on when he gets home.
I never really thought about it before but I just feel better after a walk. When I had my dog as a kid, I'd spend so much time walking (and talking to the dog) that whatever issues/problems I had would be solved. Other times, I'd come up with stories to write or various other imaginings.
Having a bad day? Take a walk.