Warming up should involve raising the heart rate, increasing ones core temperature, activating muscles, mobilising joints & ensuring readiness before commencing with higher intensity bouts of exercise. The increased temperature allows for more powerful muscular contractions and increased mobility which will help to achieve your goals quickly and safely. Preparing yourself physically has additional benefits for mental strength. Regarding health, less stress is placed on the heart, more oxygen is readily available to working muscles giving you more endurance, more carbohydrate and fat is available for energy, and the body cools more efficiently.