A passage I thought especially enlightening from the book The Art of Happiness, authored by Howard C. Cutler with the Dalai Lama:
[H]appiness is determined more by one’s state of mind than by external events. Success may result in a temporary feeling of elation, or tragedy may send us into a period of depression, but sooner or later our overall level of happiness tends to migrate back to a certain baseline. Psychologists call this the process of adaptation, and we can see how this principle operates in our everyday life; a pay raise, a new car, or recognition from our peers may life our mood for a while, but we soon return to our customary level of happiness. In the same way, an argument with a friend, a car in the repair shop, or a minor injury may put us in a foul mood, but within a matter of days our spirits rebound.
I have read about this psychological effect before, most commonly on how people who happen upon a sudden windfall — like winning the lottery or an inheritance — tend not to be any happier a year after the windfall than their than they were before they had the money.
If you’re not happy as you are, you won’t be happy even after changing external events. Happiness, if it is important to you, is best done through the changing of internal ways of thinking. Cutler shares some thoughts on how you might go about doing so (also from the same book):
Researchers have conducted a number of experiments demonstrating that one’s level of life satisfaction can be enhanced simply by shifting one’s perspective and contemplating how things could be worse. In one study, women at the University of Wisconsin at Milwaukee were shown images of the extremely harsh living conditions in Milwaukee at the turn of the century or were asked to visualize and write about going through personal tragedies such as being burned or disfigured. After completing this exercise, the women were asked to rate the quality of their own lives. In another experiment at the State University of New York at Buffalo, subjects were asked to complete the sentence “I’m glad I’m not a…” After five repetitions of this exercise, the subjects experienced a distinct elevation in their feelings of life satisfaction. Another group of subjects was asked by the experimenters to complete the sentence “I wish I were a…” This time, the experiment left the subjects feeling more dissatisfied with their lives.