Sometimes, when you want to kick things up a notch in your workout routine, a little bit of accountability is key. Which is why trainers Katrina Scott and Karena Dawn from Tone It Up created their #TIU21 challenge, the second round of which starts October 30. The three-week program is free, FYI, and includes daily workouts, healthy recipes, and tips to stay motivated. Members serve as virtual fitness buddies for each other by sharing inspiration, tips, and motivation on social media throughout. Feeling the fitspo, yet?

“Adding a little extra resistance will really help define your tush.”

Well, to add some extra motivation to your Monday, Scott and Dawn are sharing an exclusive butt workout from their challenge with Well+Good. The duo’s serious about toning and sculpting so be prepared. And if you’re looking to up the intensity of the moves below, they suggest trying heavier weights than you usually reach for. Why? “With lower body workouts, adding a little extra resistance will really help define your tush,” says Scott.

For each exercise, start by performing the first 7 reps with heavy weights (15 pounds or more), then do the next 7 reps with medium weights (8–12 lbs.), and end with light weights (3–5 lbs.) for the final 7. (That’s 1 round, FYI). Go through 3 rounds of each move.

Keep reading for 3 moves that isolate your lower bod and can help lift and tone your booty.

1. Pistol Squats

Tones your booty and thighs.

Begin standing with your weight shifted into your left leg, right leg off the ground and held slightly in front of you, a dumbbell held straight in front of your chest. Lower down as far as you can while maintaining proper form. Make sure that your knees don’t go past your toes. With control, return to standing.

Complete 21 reps on each side. You can also modify this move by sitting back onto a chair or step for more stability.

2. Step Ups

Sculpts your thighs and booty.

Start in a lunge position with your front foot on the box and one dumbbell in each hand. Squeeze your booty and step up onto the riser, straightening your standing leg and lifting your back leg behind you. Squeeze your butt at the top. Bring your elevated foot back down and return to your lunge. Complete 21 reps on each side.

3. Single Leg Deadlift

Strengthens your hamstrings and sculpts your booty. 

Begin holding a dumbbell in each hand, palms facing your body. Shift your weight into your left leg and allow for a slight bend in the knee. Hinge from the hips and lower the dumbbells down while lifting your right leg behind you. Maintain a neutral arch in your low back instead of tucking your pelvis to flatten it. Slowly return to start. Complete 21 reps on each side.

If you have 25 minutes, then you’ve got enough time to try Kristen Bell’s sprint-based workout. And if you want more Tone It Up, find out how the ladies (accidentally) built an online fitness family.