A life-changing book on happiness from the directors of the longest study of happiness in the world and the subject of one of the top 10 TED talks ever. ‘In a crowded field of life advice and even life advice based on scientific research, Schulz and Waldinger stand apart’ Angela Duckworth, author of Grit What is the key to a good life? It is a question that preoccupies us all and one that the longest and most successful study of happiness ever conducted strives t...