Well, I’ve made it to one of the major scenes that I first envisioned oh so long ago when I first was brainstorming this story, and now that I’m here I don’t know how to start. Will it ever come out as good as it has been in my head all this time? Probably not, and that is a sad realization that I must get over, so I can proceed. Because with so much buildup, it better be good!
So I must go onward and keep telling myself that any finished story is an infinite amount better than an unwritten one.
Jonas David 
I remember a similar feeling. Just go with it. Good luck