I just read a short essay about the efficacy of prayer and subsequently opened John Philip Newell’s book of Celtic Treasures: Daily Scriptures and Prayer. I found what I see as a strong example of an efficacious prayer, that is, a prayer that brings about the reality of what it expresses if we believe what we are saying. See if you don’t agree.
You have shown us love, O Christ. You have shown us God. Show us also our true face and the true face of every human being. Show us the desire for love and the strength to give ourselves in love that are woven into the fabric of our being. For we are made in the image of love, O Christ. We are made in the image of God. (p. 218)