While not attempting a strict definition of the good life, positive psychologists agree that one must live a happy, engaged, and meaningful life in order to experience 'the good life'. Positive psychology is concerned with eudaimonia, 'the good life' or flourishing, living according to what holds the greatest value in life – the factors that contribute the most to a well-lived and fulfilling life. Central theories are Diener's tripartite model of subjective well-being, Ryff's Six-factor Model of Psychological Well-being, Corey Keyes' work on flourishing, and Seligman's contributions to positive psychology and his theories on authentic happiness and P.E.R.M.A.
