I suppose there are many answers to this question. Here's one (or several strung together) for starters
I believe that the power of prayer is first felt inside of us. It's a sense of God's assent, somewhat like someone answering our phone call when the ohone has been ringing for a long time and we're wondering if maybe we should just hang up and try again another time. Then a voice anwers and simply says. "I'm listening to you." Communcation