"A young man in Bible school offered to help David Wilkerson years ago when he was ministering on the streets of New York City. Wilkerson asked him how much time he spent in prayer. The young student estimated about 20 minutes a day. Wilkerson told him, "Go back, young man. Go back for a month and pray two hours a day, every day for 30 days. When you've done that, come back. Come back, and I might consider turning you loose on the streets where there is murder, rape, violence and danger...If I sent you out now on 20 minutes a day, I'd be sending a soldier into battle without any weapons, and you would get killed."
-from "Apostolic Passion" by Floyd McClung, Perspectives on the World Christian Movement, Third Edition