I was going through some old books and found The Conquest of Happiness, by Bertrand Russell. Bantam Books priced it at 95 cents on my edition, but the wisdom inside is priceless. Here are some passages I highlighted when I first read the book:
The secret of happiness is this: let your interests be as wide as possible, and let your reactions to the things and persons that interest you be as far as possible friendly rather than hostile.
Where outward circumstances are not definitely unfortunate, a man should be able to achieve happiness, provided that his passions and interests are directed outward, not inward. It should be our endeavor, therefore, both in education and in attempts to adjust ourselves to the world, to aim at avoiding self-centered passions and at acquiring those affections and those interests which will prevent our thoughts from dwelling perpetually upon ourselves. It is not the nature of most men to be happy in a prison, and the passions which shut us up in ourselves constitute one of the worst kinds of prisons. Among such passions some of the commonest are fear, envy, the sense of sin, self-pity and self-admiration...the happy man is the man who lives objectively, who has free affections and wide interests, who secures his happiness through these interests and affections and through the fact that they, in turn, make him an object of interest and affection to many others. To be the recipient of affection is a potent cause of happiness, but the man who demands affection is not the man upon whom it is bestowed. The man who receives affection is, speaking broadly, the man who gives it.
The best part, however, is the very last page of the book. Here is a link to the book, so you can discover it for yourself.