Warming up before a workout is essential as it prepares the body for physical activity by increasing blood flow to muscles, enhancing flexibility, and reducing the risk of injury. A proper warm-up gradually raises body temperature and heart rate, allowing the body to adjust to the demands of the workout. It also helps improve performance by priming the muscles and joints for the movements they will be required to perform. Skipping warm-up can lead to strains and overall decreased effectiveness in workouts.