This exercise is best done with weights. If you haven't stocked your desk drawer with a pair of dumbbell weights, find something weighty around the office. Grab a couple of briefcases or laptop bags, or if you live in the snow belt, look behind the door for your winter boots and fill them with staplers and other weighty office toys.
Step 1: Sit upright in your desk chair.
Step 2: Holding your weights, one in each hand, let your right arm drop to your right side. Your left weight and hand should rest on your left hip. This adds weight for your right arm to lift and lower.
Step 3: Lean to your right side while continuing to face forward, and lower your right arm and weight toward the ground (and the side of your chair).
Step 4: Now lift the right arm and weight up. Go up and down on the right side eight times.
Step 5: Switch to your left side.
Step 6: Let your left arm and weight lower to your left side. Your right weight should sit on your right hip.
Step 7: Lower and lift the left weight eight times.
If you do these stretches directly to the side without allowing your body to lean forward, you will feel a nice stretch in your side and waist.
Start with two sets of eight repetitions on each side. You can increase the number of repetitions and repeat the sets as you feel more comfortable with the exercise.