Except for the few of us who are independently wealthy, we all have to do some kind of work everyday in order to live. And as the our technology advances more and more of the jobs available involve sitting for large portions of the day, if not the whole day, at a desk or computer. If you find yourself feeling stiff, achy, or in outright pain then you need to do something to help your body stay healthy and deal with the 'strain of sitting.' Obviously we all have different situations in our offices and working environments, so here are a few suggestions to help you strengthen, stretch, and relieve muscles based on some of the most common:

In a cubicle:
For cardio try alternating pumping both your arms up over your head rapidly for thirty seconds followed by alternating tapping your feet on the ground (think football drill) rapidly for thirty seconds. Just don't do it too hard -- tapping, not stomping, because other people are trying to work!For strengthening: Stretch and strengthen your back and biceps by sitting at your desk in a chair with wheels. Grab your desk with both hands (thumbs under/fingers on top) and push yourself away from the desk (your chair rolling) until your head comes all the way down in between your arms and you're looking at the floor. Then pull yourself slowly back to the starting position.

In your own office:
For cardio stand up behind your desk and take large sweeping side steps as if trying to put your feet on each side of the desk. Then march in place for 30 seconds behind your desk, followed by knee-highs for 30 seconds, and repeat the whole cycle for 3-5 minutes.
For strengthening: Stand up behind your chair and hold on to the back of it (if it swivels that's okay -- extra challenge!). Lift one leg out to the side as far as you can comfortably and hold for 2 seconds before lowering halfway back down. Lift it up again, and repeat 15 times before switching to the other leg. Do each leg twice.

In a conference room:
For cardio things can get a little crazier since you have more room. Try walking briskly around the perimeter of the room for 30 seconds, followed by shadow boxing for 30 seconds, followed by hopping in a square or doing jumping jacks for 30 seconds. Repeat cycle 3-5 times.
For strengthening: For your quads and glutes do walking lunges the length of the room, alternating the lead foot and stopping just before the trailing knee hits the ground. Do 15 reps.

There are also special stretching moves that work in each setting, so throw some of those in with your cardio and strength training moves and you'll be feeling better in no time.