Those four words can be the most important words of your life.
The World Health Organization defines depression this way: "Depression is a common mental disorder that presents with depressed mood, loss of interest or pleasure, feelings of guilt or low self-worth, disturbed sleep or appetite, low energy, and poor concentration. These problems can become chronic or recurrent and lead to substantial impairments in an individual's ability to take care of his or her everyday responsibilities."
If you feel you might be depressed, you really should seek out professional help and see what treatment and therapy options are available. Don't feel ashamed, or bashful, or afraid. Depression can truly be a silent killer. I strongly believe that if you even think you're depressed, then you need to see a doctor. Don't wait. Do it now. You'll be amazed how much the right doctor and the right information can help you. Trust me, I know it.