Sometimes I wonder, can't exercise, for example, going for a run outdoors, or even just working out with weights, be a form of meditation? This assumes that you are in good enough shape / have exercised long enough to where its basically routine, you hardly have to think while you're doing it, so you can just let your mind go blank. I think this is part of the appeal for exercise for me sometimes, I find that if I have 30 minutes to spare I like to do something active rather than quietly meditate.