1. Take a dumbbell in your hand. Lower your hand down. Your hands should be relaxed with a slight bend at the elbows. The back is straight. Put an opposite hand on the waist. This will be your starting position.
  2. Trying to fully use the shoulder muscles, lift the dumbbell at the chest level as you exhale. Make sure that your elbows drive the motion.
  3. Inhaling, lower the dumbbell down to the starting position.

Precautions: Be very careful with how much weight you use, as long as incorrect performance leads to asymmetrical muscles growth. Moreover, there is a possibility to injury the shoulder joint. Try to perform this exercise without jerks and abrupt movements.