I don't know Secretum, but it's a good question. I like what Dragonfly said tho.
I think for me, I maintain hope by looking at how far I have come. All of us have achievements, and all of us have achieved in the face of adversity.
When operating a vehicle or even during yoga classes, they tell you that your car (body) will go where your eyes are looking. And it's true, if you are looking in a direction while walking your body will want to follow. So it could be that where my mind is looking my life will want to follow suite.
I usually to to focus on positives, even when that can be hard or near impossible, I find a lot of hope in visualizing what I want, where I want to be, and how I want to feel. It feels good even just doing it, and thinking about it. I feel at peace when visualizing being at peace. I guess this falls along the lines of laws of attraction. Some people scoff at it a bit, but it seems to work for me. The more hope I can feel the more hope I can build up, over time this hope becomes a more solid foundation, gets harder to knock each time, and easier to patch back up.
I think one of the keys might be to to take statements like ~ I'm energetic now, but I've learned that that will change.~ And turn it into a statement like ~ I'm energetic now.~ Just focus on what is at any given moment, not on what if's or will be's. I know that sounds conflicting with what I said about about visualizing, but we're working on the positives here, and ridding of the negative what if's.
I hope you can find a way to get your hope and keep it. Everyone needs hope.