Dealing with discouragement

C: impossible goal
T: I can’t do this
F: Discouragement
A: moving ahead slowly
R: getting results but not fast enough
I’ve actually accomplished a lot, more than I thought I could, but the goal seems to be way in the future still. I don’t know if what I am doing is going to work. I doubt myself.
How can I encourage myself more effectively when trying to do something I don’t know how to do and have never done anything close to this?