This is beautifully and precisely stated using very few words. If you only ponder the very first sentence - I mean, really live with that sentence for a while - it will bring you considerable illumination:
Wise men and women in every major culture throughout history have maintained that the secret of happiness was not in getting more but in wanting less…. This principle has nothing to do with being spiritual; it has to do with being happy. When people feel really joyful - just glad to be alive - it isn’t because they’ve won a washing machine on a quiz show, or been promoted, or underbid a competitor on a contract. It’s because they feel good about being who they are - as is, complete, not wanting anything. Joy, in other words, comes from nothingness.