Dumbbell One-Arm Shoulder Press

Muscles worked

Filled = primary · Outlined = secondary

Source: Free Exercise DB (public domain)

Grab a dumbbell and either sit on a military press bench or a utility bench that has a back support on it as you place the dumbbells upright on top of your thighs or stand up straight.
Clean the dumbbell up to bring it to shoulder height. The other hand can be kept fully extended to the side, by the waist or grabbing a fixed surface.
Rotate the wrist so that the palm of your hand is facing forward. This is your starting position.
As you exhale, push the dumbbell up until your arm is fully extended.
After a second pause, slowly come down back to the starting position as you inhale.
Repeat for the recommended amount of repetitions and then switch arms.