Well... I wish I had more helpful things to say, but I've never dealt with anything like this. The only advice I can offer are a few things that worked for my girlfriend, who has a much milder form of depression.
I forget the author of this book, but I bet you could find it on Google. If not, I'll get back to you next week, since I'll be driving down to GA to see her on Saturday. It's called The Power of a Positive Teen, and my gf said it's made a huge difference already.
The other things that worked for us both are to focus on your prayer life. Find something, even something little, to thank God for every day, as many times as you can. The more you're heart is in a place of thankfulness, the better you'll feel about your life. We've both had this one work, and it was recommended to us by people who are experienced in this kind of field.
The other suggestion, while arguably not the most affective, is to get some positive music and play it while you're at home or in the car. "Always Look on the Bright Side of Life" by Monty Python is one of my favorites for brightening up my mood, but whatever gets you feeling happy is what you should go with.
And stop reading Rush.

Right or wrong, the guy's the biggest "negative nancy", as a friend put it, since... ummm... I guess I should have thought of someone to put in there, but yeah. Seriously though, positive influence is your best bet for helping yourself along in the non-medical realm.