Are you on medication now? Are things better?Ya it usually starts early and continues through life. I was the same. I handled it until I finally broke down and it wasn't pretty seek help now before you do something you can not take back.If your life or life style is causing the depression, it may take more change than an anti-depressant.
If your depression is severe you may need professional help. Even though that doesn't always work either.
Maybe Oddball is onto something about hypnosis
Care to talk about what you think is causing the depression?
Sometimes, there is no "cause", per se. It's just THERE. Offhand, I would bet I have been depressed since about middle school. (I have no memories whatsoever of ever actually feeling happy.)