What is Happiness?

In modern world, happiness is ill-defined. Variously refer to as contentment, joy, pleasure, satisfaction, elation, cheerfulness, and ecstasy.

Happiness is just about anything person could imagine. Happiness is a good job, good health, being love etc. Happiness is just about anything, anyone, anywhere might think of as making themselves happy.

Happiness is part of special category of mental experiences that include such positive things, as joy, pleasure, satisfaction, etc.

Philosophers have been long discussing about happiness. One of the earliest thinkers on the subject of happiness, the pre-Socratic philosopher Democritus, maintained that happy life was enjoyable, not because of what the happy person possessed, but because of the way happy person reacted to his or her circumstances.

For Aristotle he said that happiness is a kind of activity of the soul in accordant with complete virtue, there fore human must enquire the virtue.

The connection between happiness and mental health is quite strong, but happiness and the ways of reaching it has not become a part of the mainstream research in modern day.
What is Happiness?