Chances are, your office doesn't have a playground. But don't fret--there's always Twittercize! Ron S. Doyle "tweets" hourly exercise assignments that you can do at work, and they all take less than a minute. (If Twitter is new to you, leave a comment and we'll get you up to speed.) The point is, it's important to move, especially if your job is sedentary by nature. And who knows? Maybe you'll become the office Twittercize instructor!