We are all familiar with the scripture "Those that wait on the Lord shall renew their strength." That word renew also means "to exchange." A. W. Tozer says this: "I suppose it is improper to say that God makes His people strong, but we must understand this to mean that they become strong in exact proportion to their weakeness; the weakness being their own and their strength being God's. "When I am weak then I am strong" is the way paul said it, and in so saying set the pattern for every believer. What has happened is that he has switched from his little human battery to the infinite power of God."