So you’ve run non-stop for 15 minutes before. But have you ever performed 15 minutes of resistance exercise without rest? Try it with these challenging moves from trainer Craig Ballantyne. “You’ll be surprised how hard you can work without a gym,” he says. Alternate between the Y squat and the Spiderman push-up for three sets of each. Then perform the remaining three exercises consecutively (again, without rest), doing three sets of each.

Y Squat

Stand with your shoulder blades pulled back and your arms extended up and out so your body forms a Y. With your feet slightly more than shoulder-width apart, sit back on your hips to lower your body. Go as low as possible without allowing your back to round. Squeeze your glutes and push yourself back up to the starting position. Do 12 repetitions.

Spiderman Push-Up

Assume the classic push-up position with your legs straight and your abs tight. As you lower your body, bend your right leg and rotate your right knee outwards until it’s outside your right elbow. Don’t drag your foot, and try not to allow your torso to rotate. Return to the starting position and repeat, pulling your left knee to your left elbow. Do eight reps per side.

Wall Slide

Stand with your butt, upper back and head against a wall. Raise your arms so your shoulders, elbows and wrists also touch the wall. Maintaining these points of contact, bend your arms until your elbows are tucked in at your sides. You should feel a contraction in your shoulders and the muscles between your shoulder blades. Reverse the move. Do 10 reps.

Single-Leg Romanian Dead Lift

Stand on your left foot with your right foot raised behind you, arms hanging down in front of you. Keeping a natural arch in your spine, push your hips back and lower your hands and upper body. Squeeze your glutes and press your heel into the floor to return to an upright position. Perform eight reps per leg.

Spiderman Lunge

Assume the classic push-up position with your hands directly beneath your shoulders, your legs straight and your abs braced. Lift your right foot off the floor, bending your knee, and place the foot outside your right hand. Return to the starting position and lunge out with your left leg. Continue alternating legs for a total of 20 reps.