A strong core is essential for just about any physical activity imaginable, so start your New Year off right by kicking your core into action — strong and sleek abs are just one of the many positive side effects of this quick and effective circuit. The 20-minute workout is perfect prep for what is to come in our Get Fit 2015 [1] challenge. The workouts build on each other and get more challenging as you progress through the month. Your core will be involved in every workout from cardio to yoga, so let's work it!

Directions: Warm up with three minutes of light cardio. Perform each three-exercise circuit twice. Cool down with three minutes of stretching.

Circuit One: Cat Cow Series

Reps: Five in each position

• Start on all fours with hands directly under shoulders with hips and knees aligned.
• First, inhale to look up to arch your back for the "cow" portion of the move; then, exhale, pulling the abs to the spine and rounding your back like a scared cat. Repeat for a total of five reps.
• Next, keeping your spine parallel to the floor, bend sideways to look at your butt, and then switch sides. Repeat for a total of five reps.
• Finish the series twisting the spine by reaching your right arm toward the ceiling on an inhale. Exhale and rotate through your ribs to reach your arm toward the left. Repeat for a total of five reps, and then switch sides.

This series is great for creating spinal mobility, warming up your back, and waking up your core muscles.

Circuit One: Bird Dog

Reps: 10 each side

• Begin on all fours with your hands directly under your shoulders and your knees directly under your hips.
• Bring your abs to your spine to keep your torso stable as you reach your right arm forward and left leg back. Reach through your left heel to engage the muscles on the back of the leg and your butt.
• Bend your arm and leg to touch your right elbow to your left knee under your torso.
• This completes one rep. After completing 10, switch sides.

The simple move, also known as quadruped, works your abs and back simultaneously, making it one of the simplest core exercises around.

Circuit One: Alternating Backward Lunge With Side Stretch

Reps: 20, alternating legs

• Stand with your hands at your waist, and step back with your right leg into a deep lunge. Increase the stretch by lifting your right arm overhead and reaching to the left.
• Press through your left heel as you return to standing to fire up the glutes, and repeat this move on the other side.

This move stretches the front of the hips while testing your balance and working your glutes.

Circuit Two: Elbow Plank Side Step

Reps: 20, alternating sides

• Start in an elbow plank.
• Keep your pelvis stable as you reach your left leg out to the left, gently tapping your toes on the ground.
• Bring your foot back into a plank. Repeat the same movement with your right leg.

Challenge your plank by stepping your leg to the side. To modify this exercise, just hold the elbow plank for 30 seconds.

Circuit Two: Squat With Overhead Reach

Reps: 15

• Begin with your feet slightly wider than hip's width apart and toes pointed slightly outward. Raise your arms up until your upper arms are even with your ears.
• Keeping your weight in your heels, sit back into your deep squat. Make sure your knees do not go beyond your toes or roll in or out of alignment. Keep your abs engaged as you squat.
• Deepen your abdominal engagement as you press through your heels to return to standing to complete one rep.
• Do 15 reps.

Your core is challenged more by keeping the arms overhead.

Circuit Two: Rotating Deadlift

Reps: 12, each side

• Stand on your left leg with the right leg behind you with a bit of weight on your toes for balance; both knees are slightly bent. Place your hands behind head.
• Pull your abs toward your spine and keep your back straight as you hinge forward from your hips until your torso is almost parallel to floor.
• With a flat back, press through your left heel and return to standing as you twist your ribs and shoulders to the left. Your pelvis should stay still. This completes one rep.
• Do 12 reps, and then switch sides.

The addition of the twist while standing works the obliques and waist.

Circuit Three: Single-Leg Touch

Reps: 15, each side

• Begin standing with all your weight on your left foot.
• Keeping your spine long, reach forward, bending your left knee and touching your right fingers to the ground. Keep your abs engaged to keep your torso stable. Your right leg will go behind you to help you balance.
• Press your left heel into the ground as you lift your torso up to return to standing, bringing the right toes to touch next to the left foot. This completes one rep.
• Do 15 reps on each side.

Strong glutes will help keep your pelvis stable in many activities, and your abs will need to be working to maintain your balance in this move!

Circuit Three: Side Elbow Plank

Reps: Hold for 30 seconds, working up to 60 seconds

• Place your right elbow on the ground. Extend both legs out so that your body is in one straight line. Flex both feet so that you're balancing on the outside edge of your right foot. To modify, bend your left knee and place the sole of your left foot on the floor for extra support.
• Place your left hand behind your head. Reach your bottom inner thigh to the ceiling to help keep your waist lifting away from the floor.
• Maintain this position without letting the hips sag toward the floor.

This move is great for toning and tightening the sides of your waist and helps with lateral stability.

Circuit Three: Full-Body Bridge

Reps: 15

• Begin seated with your hands behind you and your fingers pointed away from you.
• Press the heels of your feet and hands into the ground as you raise your pelvis off the floor until it is in line with your shoulders and knees.
• Keep your torso in one solid piece as you lower your pelvis back to the ground to complete one rep.
• Do 15 reps.

A strong back is part of a strong core! This exercise is great for working the muscles that stabilize the lower back.