Personal trainer Charlie Chittenden usually shares his muscle-building secrets with his clients at Hero Up Coaching, and now he’s tailored a fitness routine for those isolating in small apartments—the only equipment required is a stopwatch. “This sequence will help you gain muscle, train your heart rate and release endorphins all in a fast-paced 24-minute push,” he says. Chittenden suggests alternating 20 seconds of each exercise with 10 seconds of rest in between; repeat the entire sequence eight times.

Side Plank 
Lie on your right side with your right forearm supporting your upper body. As you engage your core, lift your knees and hips off the floor keeping your spine and head neutral. Rest, then repeat on your left side.

Glute Bridge
Lie on your back with your knees bent. Lift your hips off the ground until your knees, hips and shoulders form a straight line. Keep your core engaged.

Push Up
With your hands and knees on the floor, position your hands shoulder-width apart. Extend your legs backward so that you are on your toes. Lower your body down, keeping your core engaged and elbows at a 45-degree angle. Then, push up to raise your body upwards.

Alternating Reverse Lunge
While standing upright, take a large step backward with one leg, then bend your forward leg until that thigh is parallel to the floor. Stand back up and repeat with the opposite leg.

Fast Feet
Place your feet hip-width and lower your body into a squat position. Get onto the balls of your feet by lifting your heels and start running in place as fast as you can. Be sure to stay as low as possible.