Brain stress is caused by 95% of chronic illnesses according to the document. Stress signals are sent to the brain when joints are not moving properly, from eating toxins, thinking toxins, or a lack of correct movement. These stresses can build up and stress the brain internally over time. The document recommends focusing on the three pillars of health - eating well, moving well, and thinking well - as lifestyle factors control 75% of health outcomes, more than genetic factors which determine 25%. It suggests booking a brain scan to check for symptoms of brain stress.