Brain retraining is strategic positive thinking and mindfulness. It involves getting on top of negative thoughts. You train your mind not to react to the negative. I went through a program but you maybe able duplicate the effects by reading positive thinking books and going to someone to coach you through mindfulness. Researching and worrying about health is a big factor. You do want to take care on of yourself and do what is good for your body but stop the worry associates with that. It took me a lot of work to get on top of the thoughts. Do it lovingly and happily. Even the smallest negative thought releases cortisol.