Don't hold out for a New Years resolution to whip your legs into shape. Follow this powerful seven-step circuit to build strength and tone from your quads to your calves.

Before you begin this legs workout, start with five to 10 minutes of cardio or stretching to warm up your muscles. Perform the exercises back-to-back, quickly moving from one to the next in 30 seconds or less. Do the whole routine twice, resting for two to three minutes between the first and second set.

LEG PRESS (machine)
10 to 12 reps
Sit on a leg-press machine with feet hip-width apart. Set the weight on a challenging yet doable resistance. Bend your knees 90 degrees, keeping your feet flat against the footplate. Extend your legs until they are straight but not locked. Slowly return to the starting position. Click here to learn how to perfect your form for this exercise.

LUNGE JUMPS
20 reps
Start in a right lunge position. (Your knee should be bent at a 90-degree angle, and should not pass your toe.) Jump and switch legs midair so your left leg is in front. Immediately repeat the jump, aiming to get as high as possible each time. Up for a bigger challenge? Hold a dumbbell in each hand to add resistance to your jump.

WALL SIT
45 seconds
Stand with your back against a wall. Lean back and slide downward until your knees are at a 90-degree angle. Hold this position while keeping your abs contracted.
Step it up: While holding this position, squeeze a small ball between your legs to engage your adductors (inner thighs) as well.

STANDING CALF RAISE (machine)
10 to 12 reps
Stand on the footplate with your shoulders squared. Slowly rise up onto your toes, pause briefly, and then lower your heels until fully extended. To work your calves one at a time, simply cross one leg over the other.

JUMP SQUATS
20 reps
Start in a deep squat with your feet shoulder-width apart, elbows bent at a "ready" 90-degree position. Jump up with force, making your body into a straight line in the air. Land back in a squat position and repeat.

HIP ABDUCTOR/ADDUCTOR (machines)
10 to 12 reps each
Do 10 to 12 reps on each machine. For abductor: Sit in the machine and place your outer thighs against the pads. Bring thighs away from the center of the body, and slowly return to start for one rep. For adductor: Bring thighs toward the center of the body, and slowly return to start for one rep.