Contrary to popular opinion, there is only a somewhat modest correlation between income and happiness, but it is much less so than people imagine. Material items are also way overrated. But one of the most remarkable things, I think, is that the definition, in my mind, of happiness hasn't changed much. People have always needed a portfolio of interests in their lives. And if you look at the descriptions of what makes people happy, they've remained incredibly similar over the years: healthy bodies, good, productive jobs, love, family, friends. And, on the internal side, contentment, piece of mind, satisfaction.
There really has been amazing stability of the idea of happiness across time. We still believe, for instance, in the social-comparison hypothesis--the idea that happiness is a function of the perceived gap between what we have and what we think others have. And the original concept goes all the way back to Aristotle.
Remember that the "Big Bang" achievements are not as important, in terms of life satisfaction, as the sum total of all the little moments. We need to cultivate an appreciation for the little things in life. Being able to recognize the everyday pleasures is every bit as vital as achieving new ones.
