If you've never tried it, "doodle painting" is da bomb! Just like the doodles you do with a pen while you're stuck on hold for too long, or talking to some long winded friend/relative, it is a fairly mindless activity. You can consciously choose your colors and shapes, but it doesn't have to represent anything or have any meaning other than to be pleasing to your brain, your hands, your eyes.
And...I think it is like a palette cleanser for the brain. If you're hanging onto too much angst about a painting that you're working on, this is the equivalent of jumping up and down, shaking your arms, rolling your shoulders and saying, "Whoooo!"
It is not a painting that will hang in a gallery and elicit a "Holy shit!" by the viewer (my ultimate goal as an artist). It is an "Oh, how fun!" kind of painting. So have fun!