Jerry Bridges on Power in Prayer

"[W]e must keep in mind that the Spirit of God is sovereign over when and how he works through the instruments of prayer. He certainly hears our requests and responds to them. But it's not for us to question the purposes and actions of his sovereign will. Instead we're to submit to and accept whatever he has for us. And as we respond to his answers to our prayers, we must continue to acknowledge our dependence on him through more prayer. As we cycle through our prayers and his answer in this way, our dependency grows. No wonder those who regularly practice this spiritual discipline often speak of there being power in prayer. The more prayer, the more dependency; the more dependency, the more power. The source of power is not the prayer; it is the Holy Spirit, who uses prayer as a means of grace through which he provides the power." - Jerry Bridges & Bob Bevington, The Bookends of the Christian Life