Setting my cell phone alarm for every hour gives me a reminder to do this simple thing: stand up and sit back down. Work lower body muscles and get the blood flowing. Think about it. If you do that 10 times every hour or so, by the end of your work day you've done 60 - 80 squats! Wow-- 60 squats a day is fantastic. How did I go a step further?
Ta-dah: my Wonderfully Wacky Office Chair.