There is no exact definition of the word happiness. Happy people are happy for all sorts of reasons. The key is not wealth or physical well-being, since we find beggars, invalids and so-called failures, who are extremely happy.
Being unhappy is like an infectious disease. It causes people to shrink away from the sufferer. He soon finds himself alone, miserable and embittered. There is, however, a cure so simple as to seem, at first glance, ridiculous; if you don’t feel happy, pretend to be!