"'Unless a person has a lot of psychological tools at her disposal, the mind is not a pleasant place to inhabit,' says [Christopher Germer, a clinical psychology instructor at Harvard Medical School]. 'We have evolved for survival, not happiness, and thus we have a natural tendency to focus on the negative.' When the brain is at rest, he adds, it tends to get busy revealing problems from the past and anticipating problems to come. Once we scanned for predators and poisons; now we fret over the unemployment stats and what our mother-in-law had the nerve to say at dinner."
-- From January 2013's Real Simple story on "What Your Mother Never Taught You."