The IC is a horrible, slimy-mouthed, bloodshot-eyed, filthy, stinking beast. I think every writer faces it, and most of us at one time or another have to deal with it in just about every aspect of our lives. It attacks when we're tired, when we're feeling stressed, and especially when the work isn't going well. It's easy enough to say how to deal with this monster, but how do you really put the words into action?
I've found if I say out loud (and really loudly, when I'm alone and no one can hear me talking to myself, because, really, aren't writers crazy enough?) "STOP IT. Cut it out! Don't do this to yourself!" Verbalizing the command gives it more of an impact, at least it does for me. I can choose to stick to the positive path, and I will. The dark way into negativity is no fun, so why would I want it?
Next, I reaffirm that I CAN. There's no problem you can't solve if you just work at it. The IC monster who whispers in your ear "you can't do this, it's too hard, you don't know what you're doing and you never will" is speaking in MY voice to me. WTH? If it's my voice in my head, I sure as shootin' can shut it down. And after I tell it to take a hike, I tell myself it was a lying bit of nothing, and I don't have to buy that load of offal. Sure, I can do it! What's to stop me? Only myself, and I won't do that.
Next, the argument is that your best just isn't good enough. To heck with that noise. Of course, your best is good enough. Because you're a good __________(fill in the blank). You work hard, and if you don't know what you're doing right away, you'll figure it out. My best, and yours, is an infinite number in this equation. It never runs out of room. It's all we can do, our best, and it is enough. Know it. Reaffirm it. Wear it as your writing armor.
Hope some of this helps those of you who want to throw the manuscript in the fireplace. It's saved many a book of mine, LOL!