Conditioning is a vital part of combat.  When one loses his wind or strength due to the intense demands of a realistic fight, the accuracy of movement wanes, and basically, a fighter becomes a shell of himself.  So conditioning allows for the extra time a fight might take.  Ray Hager, one of our Senior Teachers, has helped develop the Conditioning Board and even has a blog on our site that deals with the topic, even beyond the need within a real fight for a way of living that enhances the rest of your life.