"There is no duty we so much underrate as the duty of being happy."

"By being happy, we sow anonymous benefits upon the world, which remain unknown even to ourselves, or when they are disclosed, surprise nobody so much as the benefactor. The other day, a ragged, barefoot boy ran down the street after a marble, with so jolly an air that he set every one he passed into a good humour; one of these persons, who had been delivered from more than usually black thoughts, stopped the little fellow and gave him some money with this remark: 'You see what sometimes comes of looking pleased.' If he had looked pleased before, he had now to look both pleased and mystified. For my part, I justify this encouragement of smiling rather than tearful children; I do not wish to pay for tears anywhere but upon the stage; but I am prepared to deal largely in the opposite commodity. A happy man or woman is a better thing to find than a five-pound note. He or she is a radiating focus of goodwill; and their entrance into a room is as though another candle had been lighted. We need not care whether they could prove the forty-seventh proposition; they do a better thing than that, they practically demonstrate the great Theorem of the Liveableness of Life. Consequently, if a person cannot be happy without remaining idle, idle he should remain. It is a revolutionary precept; but thanks to hunger and the workhouse, one not easily to be abused; and within practical limits, it is one of the most incontestable truths in the whole Body of Morality. Look at one of your industrious fellows for a moment, I beseech you. He sows hurry and reaps indigestion; he puts a vast deal of activity out to interest, and receives a large measure of nervous derangement in return. Either he absents himself entirely from all fellowship, and lives a recluse in a garret, with carpet slippers and a leaden inkpot; or he comes among people swiftly and bitterly, in a contraction of his whole nervous system, to discharge some temper before he returns to work. I do not care how much or how well he works, this fellow is an evil feature in other people’s lives. They would be happier if he were dead. They could easier do without his services in the Circumlocution Office, than they can tolerate his fractious spirits. He poisons life at the well-head. It is better to be beggared out of hand by a scapegrace nephew, than daily hag-ridden by a peevish uncle."

Robert Louis Stevenson, An Apology for Idlers (pp. 10-12). Penguin UK. Kindle Edition.