On days when you can't seem to think clearly, get outside and go for a walk. You will quickly sense your mind's clarity and your body's pleasure with a mere five to ten minutes of activity.
Even as I type, I'm reminded that I need to do the same thing. Stress builds far too quickly and repetitively for us to ignore such a small application that brings such great rewards, whether or not the sun is shining outside.
Don't forget to stretch before and after your strides. Walking is something we should do as much as possible, not only when we're stressed or cloudy.
Guess what I'm getting ready to do next? You've got it!