It's always a matter of degree, of course, Neddiedrow, and there there is no perfect cure. For example, depending on the cause, talk-therapy may be a necessary part of things (severe trauma, etc.).
I'm not saying, "fix stuff, you'll be cured". I'm saying, "don't just take drugs and go to Work, and expect to become well again". Not that it sounds like Pressureline is doing so- he sounds like a good, hard-working dude, who's having a rough time right now, and is finding recovery tough to come by. And he's aware of what's going on, which is very important.
Treat all of the symptoms and causes. Depression is not an infection that you're going to take penicillin for and get better. While some people have a single depressive event, for most of us, it's a lifelong struggle, that starts in our late teens or early twenties. It's not going away. You need to see the low spots coming, and take care of things before you lose it entirely. Once you're out of a low spot, you need to watch and make sure it doesn't come back.
As an example of why a multifaceted approach is necessary, many depressed people get behind on things- they don't do the laundry, they neglect their schoolwork, they show up at their jobs late- little stuff, forgivable by the people around them, but most of us, at least in my culture (I live in the great Midwestern USA), feel guilty about it.
You can't just take drugs and expect all of the emotional burden of guilt over being "irresponsible" go away. I heartily recommend taking an active approach, and seeing your actions as something that will help you and help others- there is no more sure way of feeling like a good person than by doing good for others

This may or may not apply, in Pressureline's culture, and of course there are different levels of depression, which require different levels of intervention:
1. Severe depression. This is depression where people are likely to commit suicide. Obviously, this is very, very serious! Take drugs! Make sure people are around you, and aware of what's going on- you have a potentially-fatal problem, not a minor case of the blues! Stay in well-lit places, and get proper sleep! Often, this is brought about by trauma of some kind, or by emotionally distressing moments, like getting divorced, for example. Talk about it. Don't wallow in guilt and self-pity, if you can possibly help it. Remember, you aren't a bad person, even if you've done a few things you regret, and nobody wants you to die.
2. Chronic depression. This is much more common. People with it, during the lowest parts, can and do commit suicide, or self-destruct in other ways. However, most people with this condition are still "functional", albeit not at the level they should be. The best strategy varies from person to person, but combinations of drugs, talk therapy, physical activity and constructive behavior, as well as constant awareness, is part of a good coping strategy. Most of the science on depression has repeatedly supported physical activity as a vital part of a lifetime program, but again, do whatever works for you.
3. Seasonal depression (that's me). Seasonal depression is tied to solar cycles- i.e., when it's more dark, one tends to become depressed more easily, and stay that way longer. During the worst parts of winter, all it takes for me to be low for a week is a lousy day in traffic

Having read up on this topic, I use bright lights when at home, to emulate daylight, and stick to a fairly strict sleep schedule during the winter months, to prevent myself from over / under sleeping. However, it's never easy. I find, especially on weekends, that I need to peel myself out've bed, or make myself go to sleep, or I get progressively less-functional. Again, no cure fits all symptoms, but I use a variety of coping strategies- and I know what's happening, and that it will get worse, as the days get longer, so I adjust what I'm doing.