Ideally, you come away from this brief exercise with a more objective view of what really needs to be in the painting, as well as some evidence of how fresh and exciting the paint looks when you don't have time to "perfect" it.
Using the images you brought home, or ones you already have in mind, make one or two very rapid studies. If you find yourself slowing down as you get farther along, this probably means you are becoming invested in the study as a painting, and trying to make it a good one. Let go of that, too. Instead, leave out too much, and use what you learn in the next version. Keep refining the image, one version after another, adding a little of what you feel is missing, and editing out what seems to be unnecessary. Work small - no bigger than 1/4 sheet - and stay swift. Oh, and have fun.