This book presents scientific evidence revealing that happiness is good for people’s health, social relationships, job success, longevity, and altruism. The author advocates an optimal level of happiness in which people do not seek euphoria, but pursue life satisfaction, meaning, and frequent positive emotions, with recognition that negative emotions are an integral part of a happy life. It talks of the concept of psychological wealth, which extents beyond material riches, and beyond popular concepts like emotional intelligence and social capital. It also talks about how people can change their levels of happiness based on attention, interpretation, and memory. Diener brings a scientific perspective to the question at hand, giving evidence and specific things happiness effects and the ways people can alter their actions in order to be happier. This information will be important for extracting information that the reader can directly relate to; things like health, social relationships, job success, etc. It also gives evidence and advice on how people can change their actions to be happier.