This is how I tend to relax. I block out a page and begin to doodle slowly each portion until I am done. I then go back and color every part of it, finishing off with a black pen line draw.
Less Herger from http://comfortableshoesstudio.com does something called, Automatic Drawings. Which are these quick sketches that she creates by just letting her hand flow where it feels best. It's an interesting process to watch. This may not be as quick, more of a slow meditative process but it has a similar idea and outcome.