Depressive symptoms are not simply feeling miserable, but can include feelings of fear, loneliness irritability or lack of concentration, and even sleeplessness.

BBC: Depression may boost heart risk

No matter how miserable you are feeling at the moment, if you look back, there have surely been events in your life that have made you happy.

FORBES: How to Keep Happiness From Fading

Miserable employees give others the feeling that what they are doing is unworthy, spreading a sense of embarrassment amongst those who try to be passionate.

FORBES: Why You Need To Love Your Job

Anxiety and panic are quite common when one has a bad depression, and they can be more miserable to endure than the feeling of depression itself.

CNN: How long will my postpartum depression last?