Matthieu Ricard is a Buddhist Monk and delightful speaker. I really love his explanation of happiness and well-being, which can be summarized as"Well being is not just a mere pleasurable sensation, it is a deep sense of serenity and fulfillment, a state that actually pervades and underlies all emotional states; all the joys and sorrows that can come one's way. "
Beyond his initial definition of well-being, he also believes that happiness is something that each of us can choose, at any given moment, regardless of the situation. It's hard to remember, as daily events cause each of us to stumble, that we can make a choice in every moment to be happy or miserable. I strive to remember this, daily, with varying degrees of success. Here is his talk, at Google, from March 17, 2007.