If you're bored with the treadmill and elliptical, this workout is for you.
Credit: Jen Cohen

When it comes to staying fit and healthy, cardio is essential. Most of us have been conditioned (see what I did there?) to think our only cardio options at the gym are the treadmill, elliptical, or bike—all of which, let's face it, can be b-o-r-i-n-g. But I've got some news: you can get a great cardiovascular workout without actually doing cardio! Say what?

Ok, let me back up for a minute. A cardiovascular workout simply means that your body is using aerobic energy, which happens when you breathe fast and deeply for an extended period of time, maximizing the amount of oxygen in your blood. One of the ways to achieve this effect is with a training circuit.

The series below involves eight weight-training moves, but without the weights. Set a timer for 25 minutes. Perform 15 reps of each exercise, and repeat the circuit until your time is up. Whether you do this quick and energizing workout at the gym or at home, I guarantee one thing: You will not get bored.

Standing Mountain Climbers

Start by standing with your feet shoulder-width apart, arms bent with your hands (in a fist) up to your shoulders. Punch your right arm straight up above your head while lifting your right knee as high as you can. Then repeat on the left. Alternate as fast as you can until you've completed 15 reps per side.

Scissor Abs

Lie on your back with your legs straight out in front of you. Hover your legs just a few inches above the ground and place your hands behind your head. Lift your chest and your right leg up towards the sky simultaneously. Lower your head and leg back down. Then repeat with your left leg. Alternate until you've completed 15 reps with each leg.

Photo: Jen Cohen

Squat to Knee Drive

Stand with your feet slightly wider than shoulder-width. Squat down until your knees are at ninety degrees. As you stand up, bring your left knee up and twist your torso to the right, trying to touch your right elbow to the left knee. Release your leg and arm and repeat on the other side. Alternate until you've completed 15 reps on each side.

Photo: Jen Cohen

Plank Jacks

Get into a plank position with your hands shoulder-width apart and your feet together. From here, while keeping your body in a straight line, jump and spread your legs about 2-3 feet apart. Jump your feet back together and repeat for a total of 15 reps.

Photo: Jen Cohen

Lateral Shuffle to Toe Touch

Stand in a squat position with your feet slightly wider than shoulder-width. Shuffle to the right, then touch your right foot with your left hand while bringing your right arm towards the sky. Come back up to your starting stance. Then shuffle to the left and touch your left food with your right hand while bringing your left arm towards the sky . Complete 15 reps in each direction.

Photo: Jen Cohen

Ab Toe Touch

Lie on your back with your legs straight up in the air and your arms straight behind you. Using your core, lift your chest up as you try to touch your toes. Hold for 1 second and then slowly release your upper torso back to the ground. Repeat for a total of 15 reps.

Photo: Jen Cohen

Mountain Climbers

Start in a plank position with your hands and feet shoulder-width apart. Swiftly bring your left knee towards your chest, then quickly return it to the starting position. Do the same thing with your right knee. Alternate back and forth as fast as you can until you've completed 15 reps on each side.

Photo: Jen Cohen

Push Ups

Start in a plank position with your hands and feet shoulder-width apart. Slowly lower your body towards the ground, keeping your core engaged and body in a straight line. Once you've gone as low as you can, push through your arms and chest, squeeze your legs and glutes, and bring yourself back to starting position. Do 15 reps. Tip: The wider your feet are, the easier the push up will be, so find a position that is challenging but doable for you. If needed, you can also drop to your knees. Just make sure your body stays in a straight line as you perform the movement.

Photo: Jen Cohen

Jennifer Cohen is a leading fitness authority, TV personality, best-selling author, and entrepreneur. With her signature, straight-talking approach to wellness, Jennifer was the featured trainer on The CW’s Shedding for the Wedding, mentoring the contestants’ to lose hundreds of pounds before their big day, and she appears regularly on NBC’s Today Show, Extra, The Doctors and Good Morning America. Connect with Jennifer on FacebookTwitterG+ and on Pinterest.