Day 7: Back
"Let's all promise to never neglect our backs! Back training is essential because it aids in proper posture," Chadwell said. "A strong upper and middle back helps stave off lower back pain and prevent injury, and because it's part of your core, your back also helps you execute almost all other forms of exercise efficiently." You heard her — try this back-day routine, and here are some back exercises that Halle Berry does.