It's almost like you're doing squats which target everything from the glutes to the hamstrings to the calves. Stand with your leg straight and try to kick your butt with the other. There are also plenty of aerobic exercises you can do in spurts. Ideally, these are perfect if you have your own office. If you don't, take a break and hit the stairwell, the bathroom or an empty conference room. Once you've found a private place, give these simple March in place for one minute. Try this every hour. If you're looking to kick it up another notch, jump rope in place for a minute or participate in some shadow boxing for a minute or two. Another effective exercise is to perform walking lunges across the room. Of course, you can also get your workout by simply climbing up and down the flights of steps. It doesn't matter what you do - just do something.