" Scientists now understand that there is a specific “contentment pathway” that is completely separate from the pleasure or reward pathway in the brain and under completely different regulation. Pleasure (reward) is the emotional state where your brain says, This feels good—I want more, while happiness (contentment) is the emotional state where your brain says, This feels good—I don’t want or need any more. "

― Robert H. Lustig , The Hacking of the American Mind: The Science Behind the Corporate Takeover of Our Bodies and Brains