I've spent a lot of time thinking about those same questions you pose. Actually, I think pretty much everybody thinks about this at least once in a while. For some of us, we tend to see through the BS of daily life and can kind of see that the way society is set up is sort of an illusion designed to keep people performing predictable behaviors and to distract them. When you begin to think about that stuff and see behind the curtain of modern life, it can be super depressing and make you feel hopeless. If this is all there is, then what IS the point?

Typically, this is the point at which most conventional advice will tell you that you make your own purpose. That the meaning of life is to live it, and to stop trying to find meaning in life and create it. Victor Frankl actually wrote an entire book on that premise, and discussed how people in the concentration camps of World War 2 were able to find hope in their misery by recognizing their internal ability to choose their response to the situation.

That's awesome advice and it's most definitely true, but it's also one of those things that someone facing depression might reject, simply because the nature of depression is such that you feel like you have NO choice. And in a way, that's actually kind of true. The depression is onset by a mix of genetic factors and bodily processes, and a mostly chemical reaction in your brain. If anything is out of your most immediate control, it would be that (aside from the idea that if you change the types of foods you eat and what you put into your body and become more active, you can influence those chemical processes).

No, the reality came to me later after I got sick of people telling me that I can choose my attitude and that I could control something that I can only describe as coming over me like a storm inside that just leaves you feeling devastated and hopeless. The answer, I feel, comes from examining the truth and learning to accept the darkness inside. The more you resist it, the more it will persist. But if when those moments of desperation hit you, you hunker down and ride it out, the storm inside will pass. If you can cultivate a form of gratitude for that darkness (I know that sounds crazy), you can actually begin to see it from a more objective point of view and it loses its power over you.

In any case, there's not one thing you can do to move beyond this. You basically have to teach yourself an entirely new way of living and thinking about life. You have to find something that feels true to your core, and go after it with everything you can muster. Instead of fighting the darkness, you absorb it and make it your own.