You are human
It’s okay to not always feel upbeat about your situation. Some things are discouraging and scary – that’s just the way life is. It is understandable that you occasionally fall into that place where it is hard to be optimistic about your future; you are human. Those are your feelings, and your feelings deserve to be felt. Find someone you can explore those dark feelings with; you won’t get over them, but you may get though them. Just don’t drop anchor and decide to stay there forever.