Lee,
I've battled depression for a good while now. Med's arent a bad idea, if you can find one that works. Sometimes its trial and error.
Depression can be because of a slight chemical imbalance, so dont let the ego rule out meds. Ive been there done that. My ego was too big to try meds for the longest time. I took them for about 6 months and started feeling much better. I quit taking them for about 2 years. Sometimes a jumpstart is all you need.
Another thing. Force yourself to get out and have fun. Its hard as hell, but you have to do it before the depression totally takes you over. Find something fun to do, and when you start feeling down, get your ass up and go do it. Or just find something that relaxes you; music, reading, or just thinking about fun stuff. Force those thoughts in front of your depressed thoughts.
Trust me man, I have been there. Its hard to get out of, but you can do it. If you can force yourself to eat 6 times a day, you can get over this.
Friends help.