The primary purpose of a warm-up before physical activity is to prepare the body for exercise by gradually increasing heart rate and blood flow to muscles. A proper warm-up enhances muscle elasticity and reduces the risk of injury by increasing flexibility in the muscles and joints. It also helps to mentally prepare an individual for the upcoming activity, improving focus and performance. Common warm-up activities include dynamic stretches and light aerobic exercises. Overall, an effective warm-up is essential for optimizing physical performance and promoting long-term health.