Looking for a way to strengthen your shoulders? This move seems easy, but once you do a few reps, you'll see it's more challenging than it looks, since it targets the tiny muscles of the rotator cuff. If you have a shoulder injury [1], use a lighter dumbbell.

• Lie on your left side, with your knees slightly bent.
• Hold a dumbbell in your right hand, with your elbow bent, resting your upper arm on the right side of your body.
• Come into the start position, with your forearm parallel to the ground.
• Exhale to lift your right hand straight up towards the ceiling, keeping the contact between your elbow and the side of your body. Then slowly lower your arm back to the start position.
• Repeat this for 12 to 15 reps and then roll over onto your right side and do this exercise with your left arm.