4. Stair Step
Strengthens buttocks, thighs, and lower leg muscles
Find a set of steps, then clasp your hands behind your back so your arms don't help you as you climb. Lean forward slightly with a straight back, and go up two steps at a time (skipping one in between) with your right leg.

Step with the left, again skipping a step. Continue this lunge-like climb to the top, then walk down normally (without skipping any steps). Repeat for three minutes.

5. Squat Back Extension
Strengthens the buttocks, thighs, and lower back muscles
Stand with your feet shoulder-width apart, toes pointing forward and hands on your hips.

(A) Squat by lowering your hips and pushing your buttocks behind you as you lean slightly forward at a diagonal. Try to keep your back straight throughout the move, and lower as far as possible without allowing your knees to go past your toes.

(B) Squeeze your butt to stand straight, then extend your right leg behind you, lifting it until you feel your buttock muscles squeeze. Lower and repeat. Do 10 repetitions on each side, then walk for two minutes. Repeat another set of 10 repetitions on each leg.

6. Triceps Dip
Strengthens the triceps, which make up the back of the upper arms
Find a nearby bench, and sit with your buttocks close to the edge. Place your feet flat on the ground in front of your body so your knees are bent 90 degrees. (A) Put each hand by your side on the bench, with the heel of your hand cupping it, fingers pointing down. Lift your hips, and bring your torso forward so your body is in front of the bench. (B) Bend your elbows about 45 degrees to lower your hips toward the ground. Contract the triceps to straighten your elbows as you slowly push up. Point the elbows back, not to the sides, throughout the move. Do eight to 10 repetitions.

To make it harder: Bring your feet farther from your body, so there's less of a bend in your knees.