This book is about how to live a happy life, based on our everyday common sense and instincts. In the book, there are no profound theories of psychology or philosophy or science. So, every person can check easily what is said in it with the everyday real activities in his or her own life. The book is a selection of 40 articles written by the author. They deal mainly with the new definition of happiness and its valid scope, which have not been found discussed by others so far. Also, the viewpoints of the philosophers of Aristotle, Mencius and others on happiness are explained plainly by this definition.