This paper discloses and questions two assumptions on happiness that are implied by medical and technological proposals for mood enhancement. The first assumption holds that happiness consists of the indiscriminate maximization of positive and minimization of negative emotions. Second, mood enhancement implies the belief that an effortless enhancement of positive emotions will increase happiness. These assumptions are questioned by investigating the validity of the common sense slogan ‘No pain, no gain’. Support for this claim is found in literature on adversity (...) and happiness, effort and happiness, and in evolutionary psychology. From these research domains it is shown that adversity, pain, bother or effort should not always be regarded as negative experiences to be avoided in the pursuit for happiness. In some cases they can contribute to a person’s quality of life. By questioning the indiscriminate and effortless enhancement of positive emotions and avoidance of negative ones, this perspective suggests a different view on happiness than the one generally assumed by proponents of mood enhancement. (shrink)