I've been managing my depression without medication for the last few months. The things that help are trying to keep track of how I'm feeling / eating / sleeping etc., day to day, so I don't completely fall into the blackhole. I've found that taking regular exercise - about 4hours CV a week really helps. If my mood's persistently bad, I'll put in a extra long session in the evening as that's when i struggle most. I try to make sure I have a regular bedtime routine and force myself to eat a proper cooked meal at least 4 times a week.
If I've not had social - non-work - contact for more than 3-4 days, the isolation starts to really get me down, I make a real effort to fight the impulse to be anti-social and phone a friend or meet one for coffee. I will also do the opposite of what I feel at these times and accept offers to go out. If none of these are available, I'll go for a walk into town - preferrably in the sun, or even go to the cinema. If things are very bad I will pour it all out into a journal or email The Samaritans to try to put my bad thoughts into perspective.
I'm worried about how this will work through the darker months but fingers crossed, I'll manage during this toughest time of year. I don't know how useful any of this was but thought I'd post what helps take the edge off my lows. These things don't make me feel fantastic but stop me feeling desperate.