Depression can be a healthy response to difficult life situations. It may have evolved as a way for people to remove themselves from stressful activities, by eliminating their interest in them, and to ruminate on whatever complex problem is plaguing them. Depression is one of the hugest growing experiences you'll ever have. It deepens you as a human being, makes you more rational, your thinking more concrete and increases politeness and fairness. Additionally, accepting negative feelings such as sadness can, ironically, lower depression.
Thought I'd share this gold nugget with my "Action on Depression" friends. From an article in Psychology Today.