I agree, they can be helpful. I haven't used any books, but I go on Youtube and just tune in to a couple of my favorites. I find that my listening to it for 20 minutes and focusing on my breathing, my brain becomes focused. I am a serious procrastinator and have found that hypnosis has helped me. I also find that when I'm not listening to it, I still listen to the messages in my head--like a mantra. I've yet to try one for weight loss, but it's on my list.
My favorite on Youtube is The Brain Garage. Does anyone else have any favorites?