I have been paralyzed by re-reading. I have considered tossing some of my notebooks in the trash and making a fresh start. Anne Lamott says that shitty first drafts are a part of the process. I feel that I am stuck there.
I think this is probably something that everyone can relate to. I most certainly can. Usually goes something like...
Write away quite happily. Hit your target for the day. Read what you've written. Cringe.
That feeling lingers. So much more than the sense of achievement you felt when you sat down, wrote, hit your target. Which is bloody unfair as sitting down at your computer is often the hardest part.
But the re-read is, as Juliann said, paralysing. So the simple answer to getting past that bad first draft is - don't re-read.
This is, I know, easier said than done. But there are a couple of tricks to leaving out the temptation of re-reading:
Shut down immediately. Done for the day? Close your laptop, close the program, shut it down. Remove the temptation to re-read. When you sit down to write the next day, hopefully the temptation has died in the face of writing new words down.
Start a new document. Let's face it, it's incredibly hard not to re-read the next day, even if it's just to orientate yourself in the story. But that can make you feel so down about how 'good' it is that you don't write a word. So try always working in a new document. At the end of each session, paste it into a document with the rest of your story, leaving just enough behind to remind you where you were (and to prevent that blank page being so terrifyingly blank!).
Stop writing. Start dictating! Plenty of computers have dictation software, so try using that. Narrating your story out loud can help stop you making some of the cringe-worthy mistakes we're all prone too when writing. You will be less likely to overwrite this way, so you won't be horrified when re-reading by anything too purple or flowery. It's not for everyone, but I find it helps me find my voice and a more natural flow to the story than just writing, particularly a the beginning.
Par back the first draft. Maybe you need to stop worrying about creating the perfect book in the first draft - there are so many variables at play: the plot, the subplots, the characters, the prose. Why not try just getting the story out in that first draft. Get your plot out, get to know the characters and worry about the beauty of the writing later. Just getting the story out can drive you back to your computer day after day more readily than if you're wound up about finding the exact turn of phrase to set the scene. Like dictating it can also stop you overwriting and cringing when you read it back.
These are not ideas that will work for everyone, they're just things I've heard of or tried. Essentially, you have to figure out a way to get yourself beyond the shitty first draft if you ever want to finish something.
A book, a story, a poem, they all go through many drafts before they are ready for publication. It's something that we, as writers, have to accept, even if we can't embrace it.