When you only have 20 minutes to squeeze a workout into a busy day, spending time on your warmup doesn’t always feel worth it.

But consider how much sitting you do during the day: Sitting in your car. At your desk. On your couch. All that sitting restricts your ability to move well, says Nick Murtha, a coach for Men’s Health Thrive in Miami Lakes, Florida.

Related: THE 21-DAY METASHRED—an At-Home Body-Shredding Program From Men’s Health That Strips Away Fat and Reveals Hard Muscle

Sitting crunches the muscles in the front of your body, like your hip flexors and chest, and creates tightness. It weakens the muscles in the back of your body—your glutes, lats, traps, and delts in your upper back—and doesn’t allow them to contract. And it reduces your mobility in your hips and back, Murtha says.

“So walking into the gym and killing it right off the bat is going to put you at serious risk for injury,” he says. “First, you need to take time to correct the effects of sitting by loosening tightness, activating muscles, and enhancing range of motion.” To do so, Murtha uses this 3-step dynamic warmup.

“These three exercises will also prepare your body to perform at its peak by elevating your heart rate, and using movement patterns you’ll actually perform in your workout,” he says.

1. Reverse Lunge

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Do it: Stand with your feet shoulder-width apart. Keeping your torso upright, step backward with your left foot and lower your body until your front knee is bent at least 90 degrees and your back knee almost touches the ground. Pause for a deep breath, then push yourself back to the starting position. Perform 10 reps with each leg.

What it works: This movement wakes up your lower body by activating your glutes, hamstrings, and quads. It also stretches the hip flexor of your back leg.

Make it harder: With each rep, go deeper into a spider lunge. From the reverse lunge, hinge forward at the hips, and place your hands on the floor directly underneath your shoulders and next to the instep of your front foot. Straighten your back leg as best you can for a deeper stretch to your hip flexor and groin.

Related: The Ultimate Body-Weight Workout

preview for Goblet Reverse Lunge

2. Lateral Lunge

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Do it: Stand with your feet spread wide and toes facing forward. Shift your weight to your left leg, bending your knee and pushing your hips backwards to lunge to the left. Pause for a deep breath, then push yourself back to the starting position. Perform 10 reps with each leg.

What it works: The movement activates your glutes, hamstrings, and quads from an all-new direction. It also helps to increase the range of motion in your hips by stretching your inner thigh.

Make it harder: Perform the lateral lunge with your arms straight up in the air so your biceps are by your ears. Be careful not to shrug your shoulders. Try to keep your torso as upright as possible to activate your core and increase the range of motion in your upper back and shoulders.

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3. High-Knee Skip

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Do it: Stand with your feet hip-width apart. Simultaneously rise up on your left toes, lift your right knee as high as you can, and swing your left arm forward as you swing you right arm back. (Both elbows should be bent.) Each time you land, immediately repeat with the opposite arm and leg. Move forward for 20 yards, or skip in place for 10 reps on each leg.

What it works: Aside from elevating your heart rate, this exercise gets your body moving in a coordinated pattern. You’re activating your legs and arms in quick, explosive motions to wake up your fast-twitch fibers—the ones responsible for explosive power and strength.

Make it harder: Exaggerate the movement and its effects by covering more distance with each step or adding height to your jump.