At first glance, you’d expect to hear that Zuzka Light earned her taut body and sculpted abs from hours upon hours at the gym. But the social media-powered (she’s got over a million followers altogether on Instagram and YouTube) fitness star’s workouts typically take only 15 minutes. That’s right: In the time that it takes to blow-dry your hair, she’s already finished one of her signature routines.

And in this over-scheduled world, whittling down workouts is the fitness equivalent of inventing an instant green juice maker—which might explain why the Czech Republic-born dynamo has inspired a legion of loyal followers across her YouTube channel, Instagram page, and online ZGYM community with her crazy fierce, high-intensity interval training routines.

And in her book 15 Minutes to Fit, Light shares a 30-day workout program, along with her personal fitness and nutrition tips.

The crux of Light’s philosophy is personal improvement: You eke out as many rounds as you can in 15 minutes. The next time you do the workout? Try to get more reps into that same time span. “You aren’t going to hit a plateau because you’re constantly competing with [yourself],” says Light. “You’re always pushing against your personal best.”

And not only are the workouts low on the time-commitment scale, they require not a single piece of fancy-pants gym equipment. Meaning that you really can do them anywhere (sorry, excuses).

Ready to try one of Light’s 15-minute workouts for yourself first thing tomorrow? She shares a sweaty favorite from her book with us.

The Workout

This bodyweight workout combines cardio and core exercises, targeting your abs from all angles while getting your heart pumping.

Complete each exercise in order for the specified number of reps. Complete as many rounds as possible in 15 minutes. Let’s do this!

1. High Knees

Start in a standing position with your feet hip-width distance apart. Begin to run in place, bringing your knees up toward your chest as high as possible while pumping your arms. Keep your chest lifted throughout the movement and land on the ball of your foot.

Complete 20 reps.

2. Everest Climber

Start in a plank position with your hands under your shoulders. Maintain a straight line by drawing your belly button towards your spine and engaging your glutes and legs to prevent you hips and belly from sagging. Step your left foot forward next to your left hand. Then, jump up to switch legs. Land with your right foot forward next to your right hand and your left foot back at starting position. Continue to jump-switch your legs and complete 20 reps (left and right).

To modify this exercise, do mountain climbers. Start in a plank position and draw your right knee to your chest, keeping the toes off the ground. Return your right foot to starting position. Switch legs and bring your left knee to your chest. Keep switching legs—you should feel like you’re running in place—and complete 20 reps.

3. Surfer

Lie on the ground on your belly with your hands under your shoulders. Push off the ground to pop up. Land in a wide stance with your body and toes facing left like you’re on a surfboard. Bend your knees and lower your hips toward a squat. Drop down to your belly and pop-up again, this time facing the other side.

Complete 20 reps (left and right).

4. Competition Burpee Jump Tuck

Start in a standing position with your feet hip-width distance apart. Squat down, bringing your hands to the mat and jump back to plank position. Drop down your whole body to the floor. As soon as your whole body touches the floor, press back up and jump your feet forward to a squat position. Immediately do a tuck jump, where you jump up and tuck your knees into your chest. Land softly for one rep.

Complete 10 reps.

5. Side Crunch

Lie on the floor on your right side with your hips stacked and legs extended. Place your right hand on the ground in front of you and your left hand behind your head. Draw your left elbow toward your right knee by lifting your upper body and lower body off the ground like a V-shape. Be careful not to pull your head with your hand.

Complete 10 reps and then switch sides.

Ready for more HIIT workouts? Try The Barre Code’s explosive six-minute routine or this five-minute full body burn with Emily Cook Harris of EMPowered and The Fhitting Room.

Originally published December 30, 2015; updated June 7, 2018.