Here is one more powerful quote from
The Heavenly Man. Brother Yun tells the story of four demon possessed men who were a scourge on a local church. They prayed for them and immediately three of them were cleansed. However, the fourth man mocked them, and they prayed for a long time with no result. In frustration they gave up, and told the Lord they couldn't do anything. It was then that God drove the demon out of that man. Brother Yun concludes that story by saying...
"We learned a lesson that morning. When we arrive at the end of our own strength it is not defeat, but the start of tapping into God's boundless resources. It is when we are weak that we are strong in God."