Painting Your Way Out of a Corner: The Art of Getting Unstuck, by Barbara Diane Barry) have discussed interesting ways to help loosen up and expand one's creativity. One of the techniques is to paint in a manner that allows you to divest from the art itself (i.e., to be less committed to the outcome), whether that's by keeping an art journal or painting with colors you are uncomfortable using. Another technique (perhaps not mentioned in Barry's book, but elsewhere) is to paint on an unconventional surface, such as cardboard!
This work, called Watchful Eye, is 7 1/2 inches x 13 1/2 inches, acrylic on cardboard. I made a point of painting with colors that I haven't been using as of late (with the exception of cadmium yellow medium hue, as I have no other yellow to use at the moment): zinc white, paynes gray, quinacridone crimson, cerulean blue, mars black, and prussian blue hue. And yes, there is a layer of gesso underneath the painting.