I don't know what advice to give you. I've learned in recent years how insidious depression can be and that many (most?) people seem to think you can just think your way out of it. Here I mean depression as diagnosed by experts.
First, a very serious point here.
Have you seen a doctor/psychiatrist/professional about depression?
Will you if I ask you to?
Brain chemistry is crucial. A couple of hundred micrograms of acid can seriously fuck up you mind for 12 hours, what to say about a natural mis-balance over months or years?
"But... big pharma?"
Fuck that. My niece slashed the fuck out of her arms and torso and was later diagnosed and treated by some relatively mild CHEMICALS, MAN. Her whole outlook changed because she had a complex mis-balance of chemical made by her own brain.
It took several adjustments to the medicine she was prescribed, but it worked.
Having said that and if it's not depression or similar, I'd make a couple of counterpoints in the hope they might be useful to you.
I see so much wrong in the world...
Yes, there are massive global problems that (as individuals) we can't control. If you can't control it, don't focus your attention on it. You always have a choice of what to focus your attention on and we're addicted to focussing on the negative. When you pay attention to anything it grows in your mind. Don't feed the mental monsters. Easier said than done, cvhangin your mental habits is a long, slow process. The only way I know to do this is to consciously choose to focus your attention elsewhere - whether that's through meditation or some new activity or when you catch yourself focussing too much on those things beyond your control, focus on something else. It takes a lot of time and mental effort, but you're giving your subconscious instructions what you want to think about and it will respond, but not immediately.
I just don't know if it'll ever end.
Our attitude and mental state do change naturally. External conditions change too even when we have no control over them.
That doesn't make them any less dangerous or serious, but it's all in flux of varying degrees.
It can be very hard to see that when you're affected by it though, whether it's a positive state ("whoo life is great - I've never been happier, I've discovered the meaning to life...") or a negative state, like the one you;re in right now. Sometimes just knowinf that gives you a boost to see you through. Sometimes not, but it's mostly true.
Sorry, I'm not very good with practical advice, more namby pamby philosophical shit.
And I'm just a liberal wanker on the internet, but I hope it helps.