Do you have any physical (neurological) or psychiatric illnesses? (semi-rhetorical question, you don't need to answer this).
Mapping these out would probably be essential to get to the root of things and more easily recognize where things go wrong and be better able to recognize when feelings are building up before they reach a critical point to where everything collapses.
I've been depressed for some 15 years and did manage to crawl out of it. Of course it might not be possible for anyone in any situation, but it did make me realize to what extent one can shape oneself to become something that is more helpful to oneself. I'm still not in an ideal situation, I've been unable to keep jobs and going into education. My autism causes a few problems, I usually think of myself as about 1/3 retarded (though becoming aware of it does help me improve in some areas). There's also the frustrations with society, people and myself etc etc. So I do know the feels. Err, not meaning the feels are identical or of same severity.
I find that for me I have to bend negative thoughts that lead to negative feel in such a way that leaves it neutral or positive or leave a problem possible to solve at some point (not necessarily right now, but perhaps in 5 years time). Sometimes the conclusions that arise from this will seem naive to other people, possibly because of how I write/ speak (my thought to verbal/ written form isn't as precise and clear as it could be, I see things very visually mapped out and I do think I tend to come off as dumber than I am, in a way. Or maybe just difficulter to understand).
But D-: they are the result of thinking things over from multiple perspectives and settle for something that understand a negative (terms negative and positive used in a simplified manner) reality, but makes a neutral, accepting or positive spin from it. I think what changed for me was the realization of how useless depression was. It didn't solve any problems, it only made me feel like crap. So instead of being a failure who was depressed, why couldn't I be a failure who was non-depressed and who might even feel some positive feels every now and then? For me the obvious answer was the latter would obviously be a better way to be a failure, at least I wouldn't feel bad and like shit all the time.
I guess people who get out of depression have similar moments of realization. But these types of realizations are difficult to convey to others. To the depressed they will often seem dismissive, naive, non-understanding. Even if the notion is understood, the experience behind is not. And without the experience one lacks an aspect that gives the wholer perspective and understanding. Sometimes this is a subtle lack of perspective, other times it is a gaping one. In the topic of depression, it's probably more in the shape of subtle. But generally the non-depressed is unable to convey their message in a way that can be absorbed and copied to the depressed's mentality to help them get out of depression. So usually the depressed feel even worse for not being able to adhere to the non-depressed.
For me, I started the change by accepting everything. I accepted my situation, I accepted my shortcomings, I accepted that some people suck etc. This made me even sadder for a while, but eventually the acceptance started to sink in. My situation sucked, but that was ok. It didn't need to not suck. And when I screwed up, I thought "I screwed up and it's ok". I became less angry with myself when not being able to live up to what I wanted to be. I do try to have a somewhat realistic perspective of myself, but ofc it can be difficult to judge certain aspects of myself. I do also acknowledge there are some things I might be good at.
For me this made me more able to start focusing on how I could work with things, change them and do them differently. It made me more able to look for solutions and look to a future where I'd hopefully be able to change some things about my present situation. I became more at peace, and feel more at peace now and more often than I have my entire life. My emotions and thoughts are also more robust.
I do still notice tendencies to what made me depressed in the first place, so I do have to actively bend my thoughts still. It also didn't happen over night, it took months to get to where I am today. Though, depending on how you view it, you could say it took years, as I had processed a lot of crappy things from the past before the realization.
So yea, not saying it works like this for everyone, or that it's an easy or doable thing for everybody. I don't know anything about your situation, so. Point merely is that maybe some underestimate their potential for mental fluidity.
One self defeating, self defense mechanism related to depression is the idea that if you are able to get out of it, it means your problems were never severe enough to be depressed about in the first place. You can see this when a former-depressed tries to convey their experience to the depressed. The depressed will react with how the former-depressed doesn't know how it feels, that it's not so simple etc. It's a reaction to protect the ego, it thinks that if you admit it's possible to get out and change, that means your problems are minor or not important. Just a side note observation from other places, not saying it applies to anybody here.
Though one response is also admitting one should be able to do something then feel even worse for not being able to. But this is a very "it must be success right now, right here mentality". Change takes time.
