Russian Twist

Sit on floor, holding a light to medium (10- to 15-pound) medicine ball, dumbbell, or kettlebell. Tuck chin slightly, engage abs, pull shoulder blades together, keep spine straight, bend knees, and hover feet to start. Rotate torso to move the weight to the left side of the body, and reverse to right side for 1 rep. If fatigue hits, drop heels to floor.