So here's my own experience. And there's some good new and some bad news
The good news is that I have completely healed myself of a fairly serious disease using "that thing of recording my voice and listening...." (In this case I can see why you don't want to listen to it 1000s of times because you're in a hurry to get better...don't blame you)
But I also tried using the same process to heal my own back from a herniated disc.....(the recorded thing again) with no results! :/
So do I have an answer for this? Not really. I'm just trying to be as authentic as possible when I say...sometimes it doesn't work...and because of who and what I am, I attribute it to God's Will.
Did I want my back to heal more than I've ever wanted anything in my life? Absolutely...I had 4 small children that needed a mother who could actually MOVE!!
So here's what I do: I go into it with my heart full of gratitude that I will receive what I'm asking for. And if or when it doesn't work.....I am still grateful and accept it as the will of God and I always feel "blessed" for the experience and what I learn from it.
(eventually I had surgery that took the pain away, but ultimately I had to become very very hard-core in my exercise program so that my muscles supported my body enough to get rid of the pain/problem. I also learn more about prayer than I ever did in my life and other invaluable lessons)
So...you'll get lots of differing responses...and from one who's had tremendous back pain...I feel for you. Good luck!