A depressive disorder is not the same as a passing blue mood. It is not a sign of personal weakness or a condition that can be willed or wished away. People with a depressive illness cannot merely “pull themselves together” and get better. Without treatment, symptoms can last for weeks, months, or years. Depression is a common but serious illness, and most people who experience it need treatment to get better. Appropriate treatment, however, can help most people who suffer from depression.