Bicycle Crunch

"This move is awesome because it really targets your entire core," said Devan Kline, NASM-certified personal trainer and CEO of Burn Boot Camp [6]. "It doesn't take long for this move to get your muscles burning." You can up the tempo for more of a cardio challenge, as long as you maintain proper form.

• Lie on the floor with your knees pulled into your chest and your hands behind your head.
• Lift your shoulder blades off the ground and pull your abs toward your spine, pressing your low back into the mat. Don't pull on your head or neck with your hands; they're just there to support.
• Straighten your left leg out while turning your upper body to the right, bringing your left elbow toward the right knee. Make sure your rib cage is moving and not just your elbows.
• Repeat this action on the other side.
• This completes one rep.

Mountain Climbers

"The mountain climber is a fantastic low-impact aerobic exercise that is great for everyone from novices to total pros," said trainer Sarah Ray, ACE, NSCA, of Volt Athletics [7]. "It has tons of modifications that make it work for everyone." And you get a ton of bang for your buck: Sarah said mountain climbers target your core, back, and shoulder stability and hip flexor strength while pumping up your heart rate.

"This move is really what you make of it," Kline added. "You can choose to go slower and focus on building the core and shoulder strength, or you can speed it up to get your heart pumping!"

• Start in plank with your shoulders over your hands.
• With your core engaged, bring your left knee forward toward your chest. Switch legs, bringing the right knee forward while moving the left leg back. This completes one rep.
• Keep switching legs and begin to pick up the pace until it feels a little like running in place in a plank position.

Plank Walkout

The plank walkout (aka inchworm) is a full-body move you can get creative with, said Jill Brown, a certified functional strength coach and personal trainer. From the plank position, she said, you can "add a push-up or a variety of planks like leg lifts, knee tucks, knees to elbows, swivels, the scorpion, hip lunges, and so on." Here's how to do the basic move.

• Stand at the back of your mat, and circle your arms out to the sides to reach toward the ceiling. Look up, and feel your chest opening up.
• Keeping your back straight, bend forward, hinging at your hips to bring your hands to the mat. This position brings length to the back of your legs. If your hamstrings are tight, bend your knees a bit to take tension off the muscles.
• Walk your hands forward, moving into a plank, and hold each step to stretch your calves a bit. This warms up the shoulders and hands nicely.
• Hold the plank for a few seconds to really wake up your core.
• From your plank, walk your hands back to your feet until you are in another forward bend. Slowly roll up to standing, letting your head hang and keeping your neck relaxed until you're fully upright.
• This counts as one rep.

If you have space: instead of walking your hands back to your feet from plank, walk your feet forward to your hands and continue moving forward in a straight line.

Plank Jack

The plank jack is "great for focusing on total body strength," said WITS-certified personal trainer and CrossFit Level One coach Ashley Rademacher [8], "but it's primarily focussed on engageing the shoulder, core and glutes." The jumping motion will get your heart rate up as well. "The faster you move, the more challenging it is!"

• Begin in plank position, with your shoulders over your wrists, your body in one straight line, and your feet together.
• Like the motion of a jumping jack, jump your legs wide and then back together. Jump as quickly as you want, but keep your pelvis steady and don't let your booty rise toward the ceiling.
• This completes one rep.
• To modify, step out one foot at a time, then step them back in.

Side Kick

NASM-certified personal trainer Holly Roser [9] said she loves this simple but effective move for quiet, indoor cardio.

• Start with your feet hips-width apart.
• Kick your right leg to the side as fast as possible and as high as possible.
• Replace your foot on the ground.
• Continue for 20-30 reps, then repeat on the left side.

Alternating Reverse Lunge

"This is a great exercise to target your glutes and hamstrings while also using your abs and back muscles as stabilizers," said Bri Hardy, ACE, group exercise director at VillaSport Athletic Club and Spa Cinco Ranch. "The more you do, the higher your heart rate will go!"

• Stand with feet together. Take a controlled lunge (or large step) backward with your left foot.
• Lower your hips so that your right thigh (front leg) becomes parallel to the floor and your right knee is positioned directly over your ankle. Keep your left knee bent at a 90-degree angle and pointing toward the floor. Your left heel should be lifted.
• Step the left foot in, and lunge back with the right foot.
• This counts as one rep.

Elevated Tricep Dips

"This exercise is sure to get those stubborn triceps a great burn while elevating the heart rate," Hardy told POPSUGAR. You can use a sturdy chair or low table as your elevated surface.

• Position your hands shoulder-width apart on a secured bench or stable chair.
• Slide your butt off the front of the bench with your legs extended out in front of you.
• Straighten your arms, keeping a little bend in your elbows to keep tension on your triceps and off your elbow joints.
• Slowly bend your elbows to lower your body toward the floor until your elbows are at about a 90-degree angle. Be sure to keep your back close to the bench.
• Once you reach the bottom of the movement, press down into the bench to straighten your elbows, returning to the starting position. Keep your shoulders down as you lower and raise your body.
• This completes one rep.
• You can bend your legs to modify this exercise.

Speed Squat

"Using the largest muscle group in the body, the speed squat is an awesome way to light our legs on fire and increase the heart rate," Hardy said. The cues are the same as for a traditional air squat, but you'll move at the fastest tempo you can while maintaining proper form.

• Stand with your feet slightly wider than your shoulders, feet parallel or toes slightly turned out.
• Bend your knees, lowering your hips deeply. Bring your thighs parallel to the floor, and bend your elbows, keeping weight back in your heels.
• Rise back up, straightening your legs completely, squeezing your glutes at the top of the movement to get the most out of the exercise.
• This counts as one rep.
• Continue for 30 seconds, or as long as you can maintain pace and form, Hardy said.

Sliding Mountain Climbers

This tough mountain climber variation "will challenge your upper body strength while working your quads and targeting your abs," said Jenn Cino [10], NASM-certified personal trainer. "Your heart rate will be up in no time." You can use sliders or substitute towels, washcloths, or paper plates.

• With the towels under your feet (if you are on a hard floor; use paper plates if you are on carpet), start in a basic, straight-arm plank position.
• Then, as if you were actually running, pull one knee toward your chest, dragging your foot on your "slider" along the floor. As you push that leg back, pull the other knee forward quickly, like you're running or "climbing" in place.
• This completes one rep.

Lunge Pulses

Increasing the tempo of bodyweight lunges is a great way to up your heart rate and the burn in your legs, Alexander told POPSUGAR. He suggested a five-five tempo: "five seconds on the way down and five seconds on the way back up. To increase difficulty even more, try adding between five and 10 seconds of small pulses at the bottom of each rep!"

• Stand with the feet hip-distance apart. Keep your upper body straight, core engaged, with your shoulders relaxed, and your chin up.
• Step forward with your right leg, lowering your hips until both knees are bent at about a 90-degree angle. Make sure your front knee is directly above your ankle, and your other knee gently lowers softly to the floor.
• Keeping your legs where they are — right foot in front, left toe on the ground behind you — straighten back up. Then continue pulsing in this lunge position before switching sides.

Alternating Mountain Climber

Want to make mountain climbers more of a challenge? Get creative with your knee placement, Rademacher said. "Add in a crossbody rotation by bringing the right knee to the left elbow. Or, optionally, bring the right knee to the outside of the right elbow for a challenging low core and hip mobility exercise." You can do one variation at a time or combine them as shown below.

• Start in a traditional plank — shoulders over hands and weight on your toes.
• With your core engaged, twist to bring your right knee forward under to your left elbow, then bring that same knee to your right elbow to work your obliques and come back to plank.
• Repeat this with your left knee for one rep.

High-Low Plank

This move strengthens your upper body and core, said Lauren Griffith, ACE-certified group fitness instructor. You'll find that at a higher tempo, the dynamic, compound movement will get your heart rate going as well.

• Start in the high plank position on your hands and toes with your body in a straight line.
• Lower yourself down to your elbows one arm at a time, engageing your core and keeping your back flat.
• Slowly lift back up to your hands with control.
• This counts as one rep.

Wall Sit

The wall sit is a step up from a traditional air squat, said Amanda Murdock [11], ACE-certified personal trainer and director of fitness at Daily Burn [12]. "See how long you can hold it," she suggested. If you want even more of a challenge, hold weights or weight substitutes while you squat.

• Stand with your back against a wall, placing your feet about two feet in front of you. Feet should be hip-distance apart.
• Bending your knees, slide your back down the wall until your knees are at 90-degree angles. Your knee joints should be over your ankle joints, so you may need to inch your feet farther from the wall to create proper alignment. Don't let your knees fall into the midline of your body or sway outward.
• Hold for 30 to 60 seconds, and then stand up.

Alternating Side Lunge

"This exercise is great for the hard to reach inner thigh and outside muscles of the leg," said Heidi Jones, a certified personal trainer at Performix House [13] in New York City. It combines strength and mobility for a move that will work your muscles and get you sweating.

• Start with your feet directly under your hips.
• Step your right foot wide to the side, coming into a lunge with your left fingers touching your right foot. Your right knee shouldn't go beyond your right toes. Keep your chest lifted and your weight in your heels.
• Push into your right foot to return to standing, then lunge sideways to the left. This completes one rep.

Squat With Side Kick

This compound move hits all the muscles same muscles a squat: quads, hamstrings, glutes, calves, inner thigh (adductors), and core, said personal trainer Misty Tascoe, NASM. Plus, "you are left standing on when leg when you kick to one side, so this also challenges balance and stability." Push the pace while maintaining control to feel your heart rate increase.

• Stand with your feet shoulder-width distance apart, feet parallel. Hold your hands out in front of you for balance. Bend your knees, lowering your hips deeply into a squat, keeping weight back in your heels.
• Then rise back up, straightening the legs completely and lifting the right leg out to the side, squeezing the outer glute.
• As you step the foot back into shoulder-width distance position, squat down again. Then stand up and do a side leg lift on the left side. Lower the leg back to the starting position.
• This completes one rep.

Kettlebell Swing

"This is one of my favourite total-body exercises, which addresses core strength, posture, and endurance," said personal trainer Cindy Lai, NASM. If you don't have a kettlebell, Cindy recommended using a bag of laundry, a backpack with books, a water jug, or a bag of rice. "Make sure you are able to pick up the weight safely with your lower body before attempting to swing it."

• Stand with your feet wider than hips-width apart, toes slightly pointing out. Squat down, and hold a kettlebell with both hands between your legs. Make sure your back is flat and your abs are engaged.
• As you inhale, press into your feet and explode up, straightening your legs and swinging the kettlebell in front so your hands are in line with your shoulders. For a more advance version, swing the kettlebell up overhead.
• Exhale, and with control, come back to the starting position, allowing the kettlebell to swing back between your legs.
• This counts as one rep.

Sumo Squat Punch

"This is a great total-body exercise to get your heart rate up without noise," Lai told POPSUGAR. Bonus: "It's also easy on your joints." The lower you drop into your squat, the more muscles you'll use, she added. "Make sure you keep abs and glutes engaged at all times for maximum efficiency and to avoid any lower back pain."

• Stand with your feet wide, toes pointing out. Bend your knees, lowering your hips deeply into a sumo squat until your thighs are parallel with the floor. Keep your weight in your heels, engageing your abs and squeezing your glutes.
• Bring both arms in front of your face with closed fists.
• Punch to the left, initiating the jab from your waist. You should feel your obliques kick in as you punch.
• Quickly retract your arm with control.
• Repeat with your right arm.
• Return to standing. This completes one rep.