Come into a side elbow plank with your feet on the chair. Make sure your right elbow is directly below your shoulder and the left arm is extended in the air. If you don't have a rolling chair, do this Side Plank March instead.
Inhale to roll the desk chair in, rotating your upper hand down to the floor for extra stability if necessary.
Exhale, and lift your rib cage toward the ceiling as you extend your legs to return to the starting side plank position.