These aren't strenuous exercises, but you should still be careful not to overextend yourself. Ease off if you start to feel pain. You'll feel like a big moron if you pull a muscle while sitting down at your desk. And keep breathing! Most of these stretches are modified yoga poses, so the way to get the most out of them is to take measured, deep breaths whether you're practicing for half an hour or one minute.
Try a seated forward bend to stretch out your back.
Stretch your wrists.
Do a full-on chair Sun Salutation.
Use your chair to do a seated spinal twist.
And use time spent waiting by the printer/copier to do a couple wall-sits.
Take advantage of cubicle privacy to do a set of desk push-ups.
Take the damn stairs.
A ream of printer paper makes for quick and easy calf raises.
If you can swing it, swap out your regular chair for an exercise ball version.
And if you'd prefer something a little less obtrusive, invest in a hand grip.
If nothing else, work on your Kegels*.
Just remember to keep your fitness regimen ever so slightly on the DL.
