Susanne,
I know it can be so discouaging! I am not gonna tell you not to have those days or feelings because we ALL deal with them. Sometimes I will just get exhausted at the thought that I will be dealing with this for the rest of my life, I am only 45. When I start to focus on "the rest of my life" it does not take long before I am in a deep dark pit of self destruction.
I encourage you the same way I encourage myself: one day at a time. And it it's a really bad day, then one hour at a time. I rejoice in the hours and days that are good because being positive does help in so many ways.
There really IS hope. I find my hope in different ways every single day and some days are harder than others but without hope is despair. For me, my faith gets me through the darkest hours. I truly believe if God brought me to it He will bring me through it.