I liked PON but it did seem to fall under the "thanks I'm cured" or "happiness is a choice" school of personal development. It works for some people, maybe those who sometimes fall under a bad mood once in a while, but doesn't do much for real mental illness. It's like telling a lifelong alcoholic that drinking is a choice or an overweight person that eating is just a choice. How do you stay on that horse if you fall off it nearly every waking hour?