Stand up straight with your feet shoulder-width apart. Pick up a dumbbell in each hand. Lift your arms straight above your head, with your palms facing forward. Bend both elbows at 45 degrees so your weights are level with the tops of your shoulders. Do not let them touch your shoulders. Push your arms upward simultaneously, returning them to the straightened-out position. Lower. Do three sets of 12. Exhale as you lift and inhale as you lower. You will feel this in your shoulders and trapezius muscles.
Lie down with your back straight, arms at your sides and knees bent at 45 degrees, putting the bottoms of your feet flat on the floor. Lift your right arm about 10 inches off the floor, and sweep it across your body toward your head, forming a C shape in the air. Finish by extending your arm fully behind your head. Reverse the sweep, and return your arm to its original position. Repeat with your left arm. Do two sets of eight for each arm. This will give you a good stretch in the shoulders and the lower back.
Medicine Ball Swing
Stand with your feet shoulder-width apart and your arms and knees bent slightly. Hold a medicine ball at waist level, grasping it with both hands. Twist your torso to the right as you lift the medicine ball to the right, until it is about six inches above the top of your right shoulder. This is basically the same movement as the one you make when beginning a drive. Lower your arms back down to center. Repeat on other side. Start by doing the exercise three times on each side. Work up to three sets of eight for each side. You will feel this in your lower back, trapezius muscles and shoulders.