The place where I give up.
I am so much better at taking an existing first draft and threading new bits in and rearranging and fixing and rewriting, than I am at getting that first draft down.
And I pretty much always stop at 30k. I have A LOT of books that have hit thirty thousand words and are waiting patiently for me to return to them some time this century. Because, for me, making up those first weird and wobbly bits is the most unsatisfying and difficult. It is the part where it feels the least like something worthwhile or book-like. It feels, in short, like a mess.
The problem with giving up before the first draft is done is that I am essentially quitting before I’ve even started. A first draft isn’t writing a book any more than an artist’s preparatory sketches and studies are the final painting hung in a gallery.
A first draft is not the finished product, and expecting it to look like one is another step on the downward stairs to the cold and lonely cellar of self-rejection.
Basically, don’t let your first draft overwhelm you. This is not the place for perfection.