Throughout the book of the Acts of the Apostles, the church prayed and then God moved. The first great missions movement was birthed in prayer. Time and time again, the church took great strides forward because someone or a small band of people prayed. Victorious praying lays the foundation for revival. Over the last number of years, I've been a student of the great evangelical revivals, and I've discovered that all have prayer at the heart of them.
Someone gets a burden and begins to pray.
They wait upon the Lord and in His divine time, He answers their prayers. They meet with God and God manifests Himself to them. The first time that I experienced revival, there was a spirit of prayer that permeated the church and the evangelistic meetings. It began with a praying pastor. He refused to give up - to quit.