To overcome the anxieties and depressions of contemporary life, individuals must become independent of the social environment to the degree that they no longer respond exclusively in terms of its rewards and punishments. To achieve such autonomy, a person has to learn to provide rewards to herself. She has to develop the ability to find enjoyment and purpose regardless of external circumstances. This challenge is both easier and more difficult than it sounds: easier because the ability to do so is entirely within each person’s hands; difficult because it requires a discipline and perseverance that are relatively rare in any era, and perhaps especially in the present. And before all else, achieving control over experience requires a drastic change in attitude about what is important and what is not.
from Flow: The Psychology of Happiness
by Mihaly Csikszentmihalyi