The strong effects of companionship on the quality of experience suggest that investing psychic energy in relationships is a good way to improve life. Even the passive, superficial conversations at a neighbourhood bar can stave off depression. But for real growth, it is necessary to find people whose opinions are interesting and whose conversation is stimulating. A more difficult, but in the long run even more useful, skill to acquire is the ability to tolerate solitude, and to even enjoy it.

Mihaly Csikszentmihalyi, Finding Flow