Strengthens the quadriceps and improves balance and stability. Take a full stride forward with your right leg. Drop the back knee down, keeping your torso upright and your front knee over your ankle (you should be able to see your toes). Push off with your left foot and lunge forward with your left leg, repeating the move. Use your quads and outer hip muscles to keep the forward knee from wobbling from side to side. Do three sets of ten repetitions (five per leg), with a one-minute rest between sets.