[krageon]

I have made my only available mode of transportation to work (which takes me approximately 50 minutes at a fair clip) a bicycle. The regular exercise helps a lot.

Another big one is taking the time to figure out what triggers your depression. If it's seasonal, try some lights. If it's stress-related, try one of the well-established ways of combating that: If you're very energetic some kind of combat sport works well, otherwise something more calm like meditation. Try anything that sounds like it might work, and try not to worry too much if it doesn't. There's plenty of other options.

If you're a worrier, having a reasonably rigid schedule could work well. Go to sleep at the same time, eat at the same time, have lunch at the same time.

Edit: Another thing that works well is setting (very) small goals for yourself and accepting that that can be the only thing you do that day (eg "I'm going to take the laundry out of the hamper and put it in the washer"). If it's really bad, I've found that is literally the only thing that will help.