A proper deltoid workout simply isn’t complete without the seated dumbbell shoulder press. In fact, some say these shoulder workouts with dumbbells are an entire deltoid regimen unto itself, targeting the anterior, lateral, and posterior deltoid muscles (with an emphasis on the middle delts). Meanwhile, lifting two separate dumbbells (as opposed to using a machine) prevents you from using one side of your body over the other, thereby retaining firmer balance and distribution. Naturally, a fair amount of coordination is required to pull this one off, especially when you increase the weights.