Now that sweater-and-puffy-coat season has officially dawned, it can be a little tougher to say no to that pre-meal cocktail or piece of pumpkin pie. (Who’s going to notice beneath all those layers, anyway?) Which is precisely why we love Denver nutrition coach and personal trainer Amy Marolf’s approach to staying fit over the winter: You should only worry about adding weight at the gym—when you’re lifting, of course. There’s no harm in an aperitif and dessert as long as you’re exercising the right way (and eating cleanly otherwise). You can learn precisely what that right way is during Marolf’s free 45-minute ski-conditioning class on November 20 at the Cherry Creek Athleta store. In the meantime, here’s a sneak peek at some of her recommended moves.

1) SQUAT JUMPS

Work your: quads and hips

To improve: explosiveness and endurance

Which translates to: increased stamina so you can shred Highline, Vail’s long double black diamond mogul run

Step By Step: Stand with your feet shoulder-width apart and squat down. Ensure that both thighs are parallel to the ground and your knees do not extend past your toes. Jump as high as you can; land as softly as possible. Do sets of 15—at least three or as many as it takes to feel exhausted.

2) EXCERCISE BALL JACK KNIFE TWIST

Works your: lower abs

To improve: core strength

Which translates to: improved balance so you won’t face-plant when you upgrade from groomed runs to powdery bowls

Step By Step: Begin in a push-up position with your shins resting on top of an exercise ball. Keeping your back flat and your shoulders over your wrists, slowly bring your knees up and twist your torso toward your left elbow. Extend your legs back to the starting position and repeat, this time twisting toward your right elbow. Do three sets of 10 reps, alternating directions.

3) SINGLE LEG ROMANIAN DEAD LIFT

Works your: posterior chain (as in your lower back, glutes, and hamstrings)

To improve: hip strength and balance

Which translates to: more power when zipping down the hill

Step By Step: Holding a kettlebell or dumbbell in your right hand, hinge forward at the hips and bring your left leg up straight behind you. (Keep your back flat.) Bend until the weight almost touches the ground or until you feel a stretch in your hamstring, then come back up and tap your foot on the ground. Do four sets of 12 reps per side.

4) SIDE PLANK KNEE TUCKS

Work your: obliques

To improve: core stability

Which translates to: saving yourself from a wipeout next time you catch an edge

Step By Step: Start in a side plank variation (see diagram). In a slow and controlled motion, bend your top knee and bring it up toward your chest to tap it with your outside elbow. Squeeze your oblique muscles and return to the starting position. Do three sets of 10 reps on each side.

—Illustrations by Aaron Ashley