Psychologically speaking, a lot what we refer to as stress in everyday life is actually "distress." Distress comes from upsetting events such as losing your job, breaking up, flunking an exam, and so on. It throws your chemical-emotional system out of whack, and your body has to work hard to return to a homeostatic state. Several episodes of distress in a span of time can often be linked to a high incidence of illness later on.

Counterpart/opposite of eustress.