New studies reveal that sticking to the same fitness plan can cause injury and fitness fatigue, mix it up to make sure your workouts are as effective as possible!<br />Clip 1 Shutterstock, Clip 2 Shutterstock, Clip 3 Stringr, Clip 4 Stringr, Clip 5 Stringr, Clip 6 Shutterstock, Clip 7 Shutterstock, Clip 8 Shutterstock
