lunch outside
I think I just got 300% of the FDA's daily recommended sunlight for geeks thanks to Dave's great idea: eat lunch outside. The campus at work is replete with manicured landscaping, a pool, and the like. In the center of all the artificial natural beauty are a couple of park benches which I had never given a second thought to.
I'm glad Dave noticed, 'cause I don't think I ever would have.