There are simple exercises that you can do on your office chair without being noticed! Stretching relieves muscle tensions, especially for back and shoulder due to prolonged computer usage. Sit on a swivel chair. Lift your feet slight above ground. Support your body with both hands on the table. Twist your lower body to the left and right, keep your upper body straight. This helps to strengthen your back muscles. Stands up every hour for walk around. Best still if you can spare 10-min of your lunch time for whole body stretching or a short walk.