Have you ever had that moment when you’re flinging a kettlebell through the air and think, “Uh, am I even doing this right?” Yeah, us too. But without emptying your savings on a pricey trainer, it’s hard to know if your form is on point.

Fortunately, we’ve got your back. We tapped John Cianca, a personal trainer at Equinox, to tell us the six most common exercises he sees performed incorrectly on the gym floor.

“People do certain moves wrong because they haven’t been taught the right way, or because they lack the strength or mobility necessary due to what they do in everyday life—like sit at a desk all day,” he says.

Here Cianca demonstrates the incorrect form for each move. (Maybe we exaggerated a little, but we wanted to make sure you could clearly see what’s going wrong.) Then he shows the correct form so you can make the proper adjustments. For each move, Cianca also provides a modification so you can build up strength and flexibility to perfect your form.

Russian Kettlebell Swing

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Wrong: Squatting, then using arms instead of thrusting hips to lift the kettlebell. The bell droops toward the floor—more like a fling than a swing. Right: Stand over kettlebell with feet hip-width apart and chest up. Send butt back to squat and grip kettlebell with palms facing you. Drive through heels and thrust hips to send kettlebell swinging upward to chest height with arms extended. (The bell will swing forward with the momentum.) As the bell descends, shift weight back into heels while hinging at the hips and allowing the weight to swing back between your legs (thumbs to bum!). As it makes the transition from backward to forward, drive through heels and hips again (not arms) to repeat. For more detailed instructions on how to do a proper kettlebell swing, check out this article.Modification: Build up the glute strength required to thrust the kettlebell forward with bridge pose. Lie faceup with knees bent and arms by side. Engage core, press into heels, and squeeze glutesto lift hips straight up. Hold for 2 seconds then slowly lower to starting position.

Lateral Lunge

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Wrong: Stepping to the right and shifting bodyweight to the right so left leg bends instead of lengthening.Right: Stand with feet together, core engaged. Take a big step to the right with right foot, keeping toes forward and feet flat on floor. Send hips back to shift weight back into right heel. Lengthen left leg to feel a stretch in the inner thigh as you lower. Push off right heel to return to starting position and then repeat on the other side. For more details on how to do the perfect lunge, check out this article.Modification: To get the hang of this move, try a static lateral lunge first. Start with feet wider than hip width and then send hips back to shift weight into right heel. Be sure right shin lines up over right foot.Transition to the left side by sending hips back and shifting weight into left heel. In this stable stance, you’ll warm up your hip flexors and build glute and leg strength.

Side Plank

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Wrong: Letting hips sink and not using abdominals to lift and lengthen through midsection, resulting in what looks like a sexy beach pose fail. Right: Start on right side with hand directly under right shoulder, feet stacked. Extend right arm and stack shoulders in a straight line over elbow with left arm extended toward the ceiling for balance. Engage core and glutes to lift hips up, forming a straight line between head and feet. Hold for about 10 seconds and then repeat on the other side. Try to build up to 30 seconds on each side. For more on planks, check out this article.Modification: Can’t hold the plank without feeling like your core is on fire? Try this move instead: Follow the cues above but rather than stacking your feet, rest some weight on bended left leg. Repeat on the other side.

Seated Russian Twist

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Wrong: Slouching with a rounded spine and letting knees sway side to side with the ball. This is a sad seated twist. Right: Start seated with knees bent and medicine ball in hands. Sit as tall as possible, and engage shoulder blades and core to lengthen spine. Slowly rotate torso to one side. Imagine the ball is buttoned to torso and don’t allow ball to drop to floor. Pause and then rotate completely to the other side. Repeat the movement back and forth.Modification: If you’re not quite ready for the full twist with the medicine ball, try placing the ball between your legs to activate your inner thighs. Then clasp hands at chest and twist side to side with body weight only.

Bent-Over Row

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Wrong: Not pulling shoulder blades back, resulting in a rounded spine and hunched posture. This is a granny row. Right: Stand with a dumbbell in each hand. Hinge forward at hips with a slight bend in knees and arms extended so that wrists, elbows, and shoulders are in line. Engage core and keep spine straight as you use the muscles between your shoulder blades to pull weights up to chest. Slowly lower weights back to starting position and repeat.Modification: Build your strength one arm at a time with a staggered stance row. Start with one weight in right hand, step left foot into a forward lunge position, and rest left forearm on left knee. Lengthen spine and engage core to keep back straight and then use muscles between your shoulder blades to pull weight straight back to chest. Lower and repeat for 10-15 reps and then repeat on the other side.

Romanian Deadlifts

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Wrong: Having too much bend in the knees, rounding the spine, and straining back to merely lower and lift. Meh. Right: Start by standing with dumbbells in hand, resting on thighs. Keep a slight bend in both knees and engage core to maintain a straight spine. Send hips back while lowering weights toward floor until you feel some stretch along the back of legs. Push into heels and engage lower back to return to standing.Modification: A Good Morning (seen left) will help you get going with this move. Stand with feet hip width and cross arms over chest. Hinge at the hips and send butt back to lower upper body toward floor. You’ll feel a stretch in the back of your legs. Press into heels to raise up to starting position. Once you’re ready, just add weights.

Special thanks to John Cianca for curating and modeling these moves for us. He wears a Rhone shirt, his own Lululemon shorts, and New Balance sneakers. Shot on location at Equinox Highline in New York City.