Everyone occasionally feels blue or sad, but these feelings are usually fleeting and pass within a couple of days. When a person has a depressive disorder, it interferes with daily life and normal functioning. Depression is a common but serious illness, and most that experience it, find therapy helpful. It affects both men and women, but more women than men are likely to be diagnosed with depression in any given year. The vast majority of individuals, even those with the most severe depression, can get better with therapy.