Autosuggestion is a technique developed by Émile Coué (1857-1926), a French pharmacist and psychologist. It is a form of self-hypnosis that was used for psychotherapy and to increase optimism in individuals.
Believed to be related to the placebo effect, the Coué method of autosuggestion uses repetition of positive thoughts and cognitions in order to 'trick' the mind into accepting them as reality. Individuals were trained to use willpower and repetition to guide their cognitions, feelings, and behaviors to a positive way of thinking. By thinking positively, by regularly using these 'autosuggestions,' individuals were believed to overcome mental hangups and even some serious physical conditions.