br br Dr. Guevara br 678-223-3900 br br In this video, I show you 3 variations of 1 simple posture correcting exercise you can do from your office every day to counter the effects of sitting at a desk all. br br After working 8 hours or more at a desk, your shoulders tend to roll forward and your middle and upper back pay for it. This exercise will help you strengthen the middle and upper back muscles as well as your posterior shoulder muscles to improve your posture.