Do this exercise that engages your core, chest, and arms. Place a pair of dumbbells about shoulder-width apart on the floor. (A) Grab the handles and position yourself in a pushup position. (B) Lower your body to the floor and then press back up. (C) Once you're back in the starting position, pull the dumbbell in your right hand up toward the side of your chest. Pause, then return the starting position and repeat with your left hand. That's 1 rep. Try to prevent your torso from rotating each time you row the weight.