We must admit, from our human perspective it really doesn’t look like prayer is the greatest ministry. We would be inclined to think that the evangelist, who speaks to thousands of people, or the television preacher who teaches millions, or even the successful past who leads his large church membership would have larger ministries. But all of these are secondary ministries. There can be no successful evangelist, teacher or pastor without godly, praying people behind them. God’s plan is to bless and use His servants in answer, but only in answer to earnest heartfelt intercessory prayer.
John Wesley said, "God is limited by our prayer life; it seems that God can do nothing for humanity unless someone asks Him."
One archbishop of Canterbury commented that it seemed more coincidences of God’s intervention occurred after he prayed.
… The earnest (heartfelt, continued) prayer of a righteous man makes tremendous power available [dynamic in its working]. James 5:16 AMP