This is going to ramble; for that, I'm sorry.
Sometimes, all you need to keep going is something in the distance. Something that is worth surviving for - rather than something you are dreading happening, or the innevitable trudging toward a menial or unpalatable task or tedium.
I've found that while depression can lay me (and I presume other people) low at just about any time, it is always more likely to rear its ugly head when there is no pleasure forthcoming. When the light at the end of the tunnel is a toll booth or two weeks of intensive "why-don't-you-have-a-job" box-ticking, the light isn't quite so bright. Sometimes barely bright enough to justify approaching it at all.
There's several lights in my tunnel, right now. I'm very glad for that. Every day that it didn't look like anything was changing or getting better was an ordeal; now there's some things to look foward to, some opportunities and some potential.
The ensuing time - while in a very dark tunnel indeed - I spent a significant proportion of my days thinking, and several occasions led me to seeking refuge in music.
One of the things in music that I truly enjoy is when a feeling or concept or situation is surmised so superbly that it encapsulates the topic in question. Examples of this vary depending on topic, obviously. One of the topics often visited in music, however, is one that I find is rarely touched on in a way that resonates with me - that topic is, predictably, depression.
That said, there are several songs that really, truly speak to me on the subject; songs that I would refer people to if they wanted an insight into how it can feel, and it's a testament to the complexity of the condition that such songs are - given how wide a scope of music there truly is out there - terribly rare.
Several examples are Breaking Benjamin's Dear Agony, VNV Nation's Left Behind, Blue October's It's Just Me, Counting Crows' Black And Blue, and Nine Inch Nails' The Great Below. Some are bittersweet looks back; others are very much not.
My life makes more sense if I see it through the lens of music. As little as I like self-analysis - sometimes it is necessary, and having songs like this helps. Brave songs, songs that show the bare beating heart of the singer - having witnessed Trent Reznor and Adam Duritz singing their respective contributions, I can see the truth behind the sentiment, the source of the sound.
Just a ramble.