Rest days are essential in a workout regimen to allow the body to recover and repair damaged tissues. During rest, the body adapts to the stresses of exercise, leading to improved strength and performance. Overtraining can lead to fatigue, decreased performance, and a higher risk of injury. Scheduled rest enhances muscle recovery, replenishes energy stores, and balances the hormones related to stress and recovery. Incorporating rest days helps maintain motivation and long-term adherence to fitness goals.