Why live? What's the point?
I've had some problems with depression before and asked myself exactly that, but it's been a while for me. And now it's come back to me, not through my own concerns, but through the concerns of two others. I think it's worth looking at for both of their sakes.
The first person's concern is that there must be a god (specifically, the christian god) or there's no point to life. This is as full of wild assumptions as it is worrying, but the main thing I'd like to focus on here is that this person blatantly thinks our lives are not inherently valuable, that we are only any good in terms of our utility value to some hypothetical invisible magic man. If we can't do shit for him (who, I remind you, is supposed to be omnipotent), then we serve no function and our lives are worth nothing. If this person could be convinced that there is no god, the implication follows, then there'd be nothing at all to stop us from killing each other, killing ourselves and generally descending into chaos, despair and ultimately total doom. This is false for two reasons.
First, and most simply, that's clearly not what we want. Humans are social creatures and by and large we're happy to live and let live, and even to help each other, build each other up and cooperatively build massive cities and states together, regardless of faith. The suggestion that we'd all descend into chaos without christianity is automatically refuted by any functioning non-christian society, of which there are plenty. (And the same applies no matter what religion you substitute in for christianity, so clearly religion is not a crucial factor.)
Second, more abstractly, shifting our inherent value into some god's inherent value doesn't actually answer the question of what the value of existence is actually worth. If our lives are worth nothing, then what's this god's life actually worth? Carl Sagan said something similar about the age of the universe, as it relates to the existence of any god. If we ask what came before god and the answer is "nothing," then surely it's simpler to just say that the age of the universe is finite. And if the answer is "god has always existed," then the simpler answer is that the age of the universe is infinite. Why focus on a single entity within the universe when what you're really asking about is the universe in general? Something similar applies here. Why worry about the value of a single entity's life (this god thing, for example) when you're really asking if life in general has value?
So not only is this religious person's assumption pretty far from being right, but the whole approach to reaching that conclusion isn't even a very good one.
The other person's worry is simultaneously more and less concerning. It's more concerning in that it stems from clinical depression, which is not nice. But while it's more directly risky, it's at least more rational. This person's sentiment can be summed up as, "If there is no absolute value to living, and I don't feel like it, then why bother?" Which is a fair question, far more deserving of a serious answer than the god nonsense. It doesn't presuppose any magical, made-up, extra shit. That doesn't necessarily mean it's correct, but at least it's a sane start.
I would argue that it's definitely a valid argument, up to a point. If we value freedom, then control over our own bodies and minds must certainly be one of the most basic freedoms we recognise. And deciding how and when and why to end your own existence is one possible expression of that freedom.
At the same time, though, we should also value the living, not in the blinkered "pro-life" sense, which puts the not-yet-living ahead of the actual living, but in the sense of appreciating and caring for each other. On the one hand, this means we should be concerned for those who want to end their lives. Some may have thought it through clearly and sanely (those with unavoidably painful and terminal diseases, for example, have a reasonably fair claim to euthanasia), but we know full well that a great many will also have come to that conclusion because they're not wholly sane. Even something as mundane as depression, which I wouldn't describe (in my amateur opinion) as an insanity, definitely skews your judgement and ought to be treatable. So until we can be certain that death really is the kindest option, we owe it to each other to obstruct suicides.
On the other hand, this valuing of the living means that those contemplating suicide need to seriously consider the effect they'll have on those they leave behind. It's hard to think of a good way to say good bye forever, but there are also clearly bad ways of doing it: Unexpectedly, sneakily, messily, dangerously, etc.
But there's more to life than merely placating others, and more to it than merely remaining medically alive. There must be something to keep us going, something to drive us and get us out of bed in the morning; something to overcome our negative emotions and general apathy, and onward on to whatever it is that marks the difference between life and living for us. Imaginary gods fill that void for some, which you may be surprised to hear I find... problematic. For most, though, I think it's largely sexual and parental instinct that push them unconsciously along. An awful lot of behaviour can be explained, not completely but at least partly, as forms of mate-seeking or fending for offspring. I know this applies to me; I operate under the illusion that obscure, semi-private bloggers get shown a lot of unexpected but pleasing nudity (and I haven't been entirely wrong), and in the past I've always shown massive increases in proper productivity (not "for my own amusement" gaming productivity) when I have a specific lady-girl to impress. I've also converted my breeding instinct into an idea-spreading instinct, because I value my memes more than my genes, and I express this through my teaching/tutoring and my writing, plus my small contribution to the skeptics' movement.
But what about those for whom none of those standard motivations seem to apply?
I'm sure there are other possibilities, but I only have my own experience to draw on here, and what springs to my mind is something some dead, old, white guy once said, or alternatively two things that my mom used to tell me. The former said something poetic about humans needing a combination of both love and work to get by. That's kind of what I'm getting at, but it's a bit vague. The latter gave me two apparently contradictory instructions as the "most important rule" I should try to live by, and it took me a long time (and perhaps some dead, old, white guys) to figure out how they fit together. The first instruction was, "First the work and then the play," a parental thing about cleaning my room before playing in it and messing it up again (incidentally, I've now streamlined that process by simply never cleaning my room and thus having everything ready at hand to play with). The second instruction, given to me on my very frightening first day of school, was, "The most important rule is to have fun."
The only logical way I've found to follow both of those instructions, those Laws of Shambotics, is to have fun while working. That's true enough in the limited sense of earning a living; I've done boring and unpleasant jobs and couldn't stick with them. But I prefer to take it beyond that, defining "work" as anything that takes more effort than vegetating in bed, whether it's going out for a night on the town or moving house or driving grandparents to doctors' appointments. Anything that's "work" must come before you can play. Even going out to see friends for something hopefully fun still takes the effort of getting off my arse and dressed and into the car. And while a lot of that might seem trivial to many people, depression makes the smallest effort seem insurmountable. (And failure to achieve what you intellectually understand to be trivial only makes you feel worse, compounding the problem. And don't even get me started on how shit it feels when people who don't know what it's like - probably don't even know you have a problem - give you additional shit for this failure.)
But! The most important rule is to have fun! My great epiphany was in realising that the instructions work in parallel, feeding off each other. Not only is that initial work necessary to get to the fun playing stuff, but the work must also be fun, or at least must be made fun. Years of roleplaying helped, and now I sort of LARP my way through the day. Looking for an unknown address isn't tricky driving and time wasted, it's a voyage of discovery. Putting myself out in the dark pit of dating despair isn't making myself socially and emotionally vulnerable, it's an opposed charisma check (that both sides are hoping to fail, oddly). Sending out CVs isn't a depressing chore, likely to end in many outright rejections before there's even a single interview, it's LFG, it's the endless, aimless nights in random taverns that must occur before the group of PCs happens to meet up together by chance for something more exciting.
It don't mean all of this completely literally. I don't stop before every task to figure out an acceptable geek analogy; it's just an attitude thing, a willfull attempt to put a more comfortable spin on the uncomfortable. With practice, it becomes an unconscious habit. And of course it doesn't always help, but it's something. It's a way of framing the world in a way that makes it more appealing and thus worth living in.
And that, I think, is largely all the big secret is: Perception. Change your way of looking at life and you can make it either worth living or not. This is not an easy thing to just change overnight, especially if the chemicals in your brain aren't helping, but it certainly can't change if you yourself are the one unwilling to let it.
Now, I know how fucking miserable it is to be told to just "cheer up," as if it were a single, little switch to throw, so I'll simply leave this picture here, for no particular reason...
So, to sum up (gosh, that's a lot of semi-complete thoughts to try and process), life's a piece of shit, when you look at it, but you don't need imaginary gods to make it worthwhile. You don't even need real gods. You don't strictly even need real people to enjoy your life, though the way we're evolved, as social creatures, it does usually help. Your happiness, your self-worth, the value of your life and living, these are all things inside your own head. If they're not working for you, then you need to address it. I don't deny that therapy, drugs and good friendships are also important if you're properly depressed, because brain chemistry is not something to be underestimated. But for most people, the value we give ourselves is really all we can be sure of, and if you can't give yourself a respectable dose of self-respect, without first having to prostrate yourself before others, whether real or imagined, then you should be worried about yourself. Value your own life. Value the lives of your fellow sentients. And try to have fun. It's all we've got.