Weighted Zercher Squats

Stand holding a sandbag or weighted fitness ball (about 10 pounds) at chest height with your arms underneath and forearms crossed. Your feet should be shoulder-width apart, toes pointed slightly outward. Pull the bag or fitness ball in toward your chest and keep your shoulders from shrugging.
Squat down while pushing your hips back as you bend your knees. The weight will try to pull your torso forward so be sure to fight to keep your body upright. Perform 12 reps quickly, taking one second to go down until your thighs are almost parallel with the floor — don’t pause at the bottom — then push up as fast as possible while maintaining good form. Pause briefly at the top and repeat.