It's not easy Jamie. But you're not on your own. You may have "Low Mood" which some Doctors refer to instead of depression as it doesn't carry any kind of stigma with it, and to be fair, is not as bad as the real thing. Everything that's been posted in reply is bang on from what I can see.
There are studies that confirm that exercise is a very good antidote to depression but I think it's got to be exercise you enjoy. Running would just drive me into a terminal decline but cycling is something I really do like.
Good luck with your fight back and, as I think you can tell, you won't get the p**s taken out of you on here.
Don't forget your mates though. They were your mates before you started feeling crap and they'll probably still be your mates afterwards.