This semester I'm working in a computer lab. With my arthritic knees and hip I can't do a lot of standing or walking around, but it doesn't help to be seated all day either. Thanks to Spark I found ways to avoid stiffness and burn a few calories.
First I set up my online timer - timer.onlineclock.net/of f.html for 30 minutes. When it goes off I do one of these before re-setting it for another 30 minutes.
I also keep a travel cup or water bottle by me which I get up and walk about to refill (and drinking regularly, I also have to make trips to the restroom!) so by the time I finish my day I've drunk my 8 cups, and avoided the stiffness that used to settle in.