My good friend has depression. He's learned to deal with it and has agreed to live with it for the rest of his life. At the same time, he hasn't lost hope that his depression will end. Some people suffer from depression for years, even decades and somehow their depression ends.
This is kind of funny, but true: He was hit by a car a few years ago and his depression was almost totally gone for almost a year. We often joke that I should hit his head really hard once a year and that should do the trick. But seriously. He was hoping it would never come back. Unfortunately it did, but that experience gave him more hope that there must be something that will eventually help him for good.