Internal body use challenges conventional wisdom and the conventional application of strength. The body must be strong. The application of that strength is unorthodox. The aim is to unite the entire body in application. Every action is a complete action. Every part of you does every movement. This may sound strenuous but it is not. Instead of delegating the workload to your arms and shoulders, every part of the body is involved. Instead of forcing your will upon the entire attacker, you limit your attention to a small part of their body and use everything you have on that target. The strategy comes from The Art of War.