If you believe that you can say words, or take a pill, or go thru a surgery and be cured–without a doubt, or with the full support of someone who has no doubts–you will experience a cure. This is not because there’s someone “out there” listening to and answering your prayer, but because your subconscious body-mind has been convinced that the thing you are doing will get rid of the symptoms you’ve been focused on. To that extent, as Norman Cousins says, “the history of medicine is the history of the placebo effect.”
That having been said, there’s increasing evidence, supporting thousands of years of anecdotes and teachings, that say that if one enters into a state of consciousness in which one feels what some traditions call “the peace that passes understanding” then, like the tumblers of a lock falling into place, a variety of conditions are shifted–and that the same thing happens for the people and animals we focus on as we enter that state of consciousness. The process by which this happens is outlined in the book I helped write: Calm Healing: Methods for a New Era of Medicine.
There’s lots of work being done on this, some sponsored by the National Institutes of Health and the National Science Foundation. The Institute of Noetic Sciences is the leader in the field. My book, Uncommon Prayer, explains how to get to that state of consciousness. If you don’t like books, watch the videos: What The Bleep Do We Know? and Matrix Energetics.