I'm going to keep this short because I've got writing to do and so do you:
I struggle every day. Every single day I write I wonder if what I'm writing is any damn good. Yesterday was not a bad day writing, just a slow one. Missed my word count by a significant number but still got over 1300 words in. I'm approaching the dreaded Middle of the Story and so far I'm off the plan I had for the book. That doesn't mean I won't get back on track and that the writing won't continue to be a struggle but I've got a goal.
So do you. You can do this. All you have to do is sit down and stop thinking and start writing.
I know it sounds hard but that's the point, isn't it? If it was easy everyone would do it. The hard is what makes it great. (Plus there's no crying in baseball, remember that, too.)
Do what you have to, but don't give up. It's not impossible. You're not the only one who has to work hard at this. Ask anyone in the group or on the forum. They'll tell you, too.