The blonde beauty recently revealed that heading back to the gym after giving birth to her second baby helped her shed 61 pounds. One move she relied on: the Single-Arm Single-Leg Romanian Deadlift. “With this movement, you’re balancing on one leg, causing your hip to have to stabilize, as well as working the back, glutes, hamstrings, and core,” says Lively’s trainer, Don Saladino, owner of Drive 495 in New York City.

Stand tall with feet together and a dumbbell or kettlebell in right hand at thigh and left arm out to side for balance. Hinge at hips, lowering torso until almost parallel to floor as you lift right leg behind you, toes facing down. The weight should travel straight down in front of right leg. Return to start and repeat. Aim for 2–3 sets of 8–10 reps per leg, three times a week.