Health is generally considered to be freedom from disease. However, health also involves the state of the mind. If you are satisfied with life, if your mind functions accurately, and if you possess enough force, driving power, and impetus to give you confidence in yourself and the ability to accomplish your work, you have good mental health.
Happiness has been described as a balanced flow of energy and the satisfaction of desires. You are happy if you get what you want. Many people do not know what they want. People differ in the things they want. Everyone who is ordinarily healthful is interested in getting enough to eat and enough rest, and in satisfying the ordinary desire for reproduction.
There are different levels in fundamental desires. Some people get hungry without really needing food; others require far more rest than do average people. The nature of any desire is conditioned by experience and knowledge, and a person who has never eaten strawberries is not likely to crave strawberries.
An unsatisfied wish is a driving stimulus until it is satisfied. Good mental hygiene requires a certain amount of rationalization. Rationalization is a term used to describe the ability of a human being to satisfy himself with what he gets rather than constantly to be wanting something that he cannot have.
Because it is possible to find happiness with less than a maximum of the desires we have, mental hygienists suggest that everyone develop as a major interest not only a job but perhaps some hobby or game in which he may achieve the success that it is not possible to reach in another field.
The basic rule for a happy and contented mind is to cultivate certain standards of living against unexpected changes and then, so as not to be incurably depressed when you fail to achieve something you want, maintain a flexible attitude of mind.