Also… I have a theory about this:
I just can’t see any purpose or point in life or any time when I won’t feel this low.
My theory is that it's actually impossible to imagine feelings and moods, at least, not in the way we might imagine a tune or an object.
Imagining a tune or an object does not conjure those sound vibrations or that physical object into existence.
But a feeling or a mood isn't a physical external thing that your brain only creates a representation of — it's an internal state, and by "imagining" that feeling or mood, what you're actually doing is not just imagining it, but producing that feeling or mood in yourself, to some extent or another. To imagine feeling sad, you create something of the feeling of sadness inside you.
So my theory is that in certain very strong mood or emotion states, it's actually impossible to "imagine" you will ever be able to feel different, because in order to do so you'd have to overwhelm a very strong existing mood or feeling with the one you're trying to create.
Depression is so powerful that it removes your ability to conceive of positive moods and feelings in the future, because it's impossible to create a version of them now.
But it's absolutely not true that you will never feel any different. It's just a cruel trick of depression.
That's my theory anyway — take it or leave it 