Stand with feet hip-width apart and arms at your sides. Slowly step back with your left leg so both knees bend at about 90-degree angles (making sure forward knee does not extend past toes). At the same time, allow your arms to come forward to shoulder level to help with balance. Hold lunge position for four counts. Return to the starting position, and perform lunge on opposite leg. Do two to three sets of 10 to 12 repetitions on each leg.
Try a walking lunge: Stand at the end of a long hallway or room, and take a large step forward with your right leg, landing on your heel first. Slowly lower your body until both knees are bent at 90-degree angles. Lift from the heel of front leg to stand without pausing, then continue stepping forward, this time with your left leg. Perform 10 to 12 times on each leg.