Hey, it's okay to feel what you are feeling. Also, I can't give you any reason to be optimistic because you need to find one yourself.
We all have those days when everything seems bleak and there's no point in going on anymore. But we have learned to push ourselves just a little bit further. And the good news is that you can learn that too. It's really a skill just like you would learn to ride a bike. You may need some help, either professional or from your close and trusted friends.
Until you seek help, here's what you could do. Do small things that increase your confidence. How about you try to wake up early at 6 am for a few days. Just for the sake of it. Push yourself to go out for a walk. Or talk to an old friend. Do small things that seem difficult but really aren't. Collect these small achievements like you would collect rewards in a game. You will slowly gain confidence in yourself and you will automatically see your mood get better.
Again, I would still recommend you get some professional help. Hope this helps you.