From what your saying, I don't think you have a depression bad enough where you need to see a doc.
My wife has serious clinical depression, so I know a little about it.
For the physical aspect of it all, I recommend the "Body for Life" program.
Link to the audio book:
http://www.amazon.com/exec/obidos/AS...086827-8266252
I know a lot of the hardcore fitness people may not like the guy, but I personally think what he's set up is great. Besides going over workout routines and eating, he insists on setting up goals for yourself. Get the audio book, its really good, and it will get you pumped up. I lost 30 lbs doing it.
Being overweight can really drag you down. It'll suck your energy away.
If you decide to not check into it, at least consider to make a goal each day of doing something that you'd like to do, but never do. Resolve to NOT turn on the TV for at least a day. Say to yourself, "I'm going hiking at 4:00, dammit." Tell a family member that you want to go hiking at 4:00, and to badger you if you don't go. The hardest part will be walking out the front door!