6 of 8

Core: Scissor and thread

Sit tall on the floor with legs extended in front of you, holding a 4- to 6-pound medicine ball (or dumbbell) in both hands. Tighten abs and hinge back slightly at the waist. Keeping your left heel on the floor, raise your right leg as you transfer the medicine ball to your right hand and circle it over, then under your right thigh.

As the ball comes under, transfer it to your left hand, lower your right leg and raise your left, and continue the figure eight–style ball movement on the left.

Next: Core: Circle arm squat