You live because there is only one alternative. Mind you, you can choose that alternative, but very few people genuinely want to do that, and I don't think it is to be recommended at all. You just really, truly, never know what is just around the next corner. Your life can do a 180 between one day and the next, and you just never know how it will turn.
Also, I personally don't believe in living on hope. If I spend my time hoping that in the future things will be better, then I am not focusing on what is happening right now. If I live only for future Hopes, I might miss the joy that a bird song or a sunset or even just the most perfect little breeze can bring to me. I want to live for right now. And if right now sucks because I am in pain, then I remind myself that at least I am in pain inside my own dwelling! I have a roof, shoes I can put on if I go outside, and food to eat. Millions of people don't have all that, and are also in pain.
Usually you are better off than you think you are. You just need to focus on it. And I am not some Pollyanna who is saying that thinking positively will change the world or even your life. Just saying that it can't hurt, and I have found that it makes this moment better for me if I actually am alive to this moment right now.