Set-up: Position a stability ball in front of you and rest your knees on a mat.
Lift: Place your forearms on the stability ball. While bracing through your core, slowly rotate your forearms in circles in a 'stirring' motion. Perform half of the recommended repetitions circling clockwise, and the other half counter-clockwise. Note that your knees, hips and shoulders should form a straight line. Do not let the hips sag or pike to accomplish this movement.