Why you need them: Bicep curls may be old school, but they're still the best way to slim and define not only the upper arms, but the forearms and shoulders as well.

The breakdown: With your weights in hand, begin by standing with your feet hip-width apart, knees softened and abs engaged. Step slightly forward with one foot, making sure that the heel of the back foot is raised off the ground with only your back toes touching the floor. Exhale as you raise the weights towards your chest, and inhale as you lower the weights back to your starting position. As you raise and lower the weights, be sure to keep your arms parallel to your body and your elbows squeezed to your sides.

Why you need them: Dips target the back of the arms (you know, the part of your arms that seem to wave back at you ). "You can't forget about the view from behind when wearing a tank top," Bridges says of this toning exercise.

The breakdown: To begin, sit low on the bench making sure that your knuckles are facing your back as you grip the edge. Slowly walk your legs forward until your thighs are parallel to the floor keeping your feet flat on the ground. As you inhale, lower your body until your upper arms are almost horizontal, then exhale as you bring yourself back to your starting position.

Why you need them: Like the name says, presses work your shoulders, which helps create that tapered look that gives you the illusion of a smaller waist.

The breakdown: Start standing tall with your feet in a staggered stance. Grab your weights, and with your palms facing out, bring them to chin level. Keep your arms slightly forward as you exhale, raising your arms up. Inhale as you slowly bring your arms back to your starting position, making sure that you keep your abs held tightly the entire time.