For much of my life, I, like most people, regarded the pursuit of happiness as largely a selfish pursuit. One of the great revelations of middle age has been that happiness, far from being only a selfish pursuit, is a moral demand.
When we think of character traits we rightly think of honesty, integrity, moral courage, and acts of altruism. Few people include happiness in any list of character traits or moral achievements.
But happiness is both.
Happiness -- or at least acting happy, or at the very least not inflicting one's unhappiness on others -- is no less important in making the world better than any other human trait.
With some exceptions, happy people make the world better and unhappy people make it worse. This is true on the personal (micro) and global (macro) planes.
On the micro plane:
Consider the effects of an unhappy parent on a child. Ask people raised by an unhappy parent if that unhappiness hurt them.
Consider the effects of an unhappy spouse on a marriage.
Consider the effects of unhappy children on their parents. I know a couple that has four middle-aged children of whom three are truly extraordinary people, inordinately well adjusted and decent. The fourth child has been unhappy most of his life and has been a never-ending source of pain to the parents. That one child's unhappiness has always overshadowed the joy that the parents experience from the other three children. Hence the saying that one is no happier than one's least happy child.
Consider the effects of a brooding co-worker on your and your fellow workers' morale -- not to mention the huge difference between working for a happy or a moody employer.
We should regard bad moods as we do offensive body odor. Just as we shower each day so as not to inflict our body odors on others, so we should monitor our bad moods so as not to inflict them on others. We shower partly for ourselves and partly out of obligation to others. The same should hold true vis a vis moods; and just as we avoid those who do not do something about their body odor we should avoid whenever possible those who do nothing about their bad moods.
The flip side of the damage unhappy people do when they subject others to their unhappiness is the good that people do when they are, or at least act, happy. Just think of how much more you want to help people when you are in particularly happy mood and you realize how much more good the happy are likely to do.
On the macro plane, the case for the relationship between happiness and goodness is as apparent.
It is safe to say that the happiest Germans were not those who joined the Nazi Party. Nor did the happiest Europeans become Communists. And happy Muslims are not generally among those who extol death. The motto of Hamas and other Islamic groups engaged in terror, "We love death as much as [Americans, Jews] love life," does not appeal to happy Muslims.
Cults, hysteria and mass movements all appeal to the unhappy far more than to the happy. It is one more example of the genius of America's Founders to include "life, liberty and the pursuit of happiness" in the Declaration of Independence. No other major civilization so enshrined happiness as a core value. This American belief in the moral and societal merit in pursuing happiness is a major reason America has developed differently than Europe. The American emphasis on happiness is one reason no fanatical political or religious movement, Left or Right, has been able to succeed in America as such movements have repeatedly succeeded in Europe.
The pursuit of happiness is not the pursuit of pleasure. The pursuit of pleasure is hedonism, and hedonists are not happy because the intensity and amount of pleasure must constantly be increased in order for hedonism to work. Pleasure for the hedonist is a drug.
But the pursuit of happiness is noble. It benefits everyone around the individual pursuing it, and it benefits humanity. And that is why happiness is a moral obligation.