You're not the only person who feels like this.
Depression is a terrible experience in that it alienates you, it does make you feel like you are the only person experiencing it.
I believe depression is usually triggered by something. It is caused by things that are very real, things we experience in our life, it is not something we make up, in order to make ourselves suffer. It's the way our body responds to extreme disappointments, over and over again.
For me personally, even though I want to improve, it comes back. I think it's the same for basically everyone fighting depression. It always seems to come back and say "No, there is no point." When you are trying to recover, the depression does come back when we experience another disappointment. It's like disappointment or bad events just trigger the feeling that there is no point.
I do believe in recovery from depression, but I do think that the person recovering has to be wise and know that your brain is going to make you feel like this again. Recovery is a long curve in that way. It starts with recognising something isn't right, but the road is much much longer than that. It takes commitment. Even if you start integrating good things into your life, there will be days where you just give up on them. At the moment, I'm at the giving up point, where I see no hope, but at least I can write this to you and anyone out there suffering, and have some kind of solidarity and shared experience.
Depression truly makes you feel that there is no hope, but there are small signs of hope, like the fact this forum even exists. It's so easy to convince ourselves that everything is hopeless, and really take on that feeling, but if you try, just try to bring yourself back to the point where you recognise the smallest, tiniest bit of good thing in your life. We need to help each other to get back on the good path, when all hope is gone. Sometimes we just find hope in other people, because they give us that push.
There are things that can bring you out of it and make you feel less alone in it. Sometimes reading something you relate to, sometimes talking to someone, sometimes just telling yourself "this is just a blip on the road to recovery, this will pass". Of course, when you're in it, it feels like it will never pass. Aim to get to the point where the depressive episodes are fewer and fewer.
I don't want to belittle anything that you or anyone with depression is going through, because I know how real it is. It's a long game, and a long struggle, of carrying on, and keeping on carrying on. In dark moments you won't even be able to see why you are trying.