Don't tell me that I'm the only one who has periodic bouts of insecurity and thoughts of, 'This whole thing just sucks!' I'm not alone, am I? [LOL That sure sounds insecure]
It comes around less frequently, but it's still there. It's an odd dichotomy, because part of me is also quite confident while this naggy, Doubting Thomas syndrome clings on. Klingon?
I've started to recognize it as a symptom of frustration. Usually it stems from my perfectionist tendancies and knowing something is not perfect. For instance, I made a note that I never described the interior of one of my spaceships. It's a very minor thing and it's easy to insert that later and I know exactly where it needs to go. Yet I start to feel like the whole manuscript is a mess because of it.
It goes a long way to recognize the insecurity for what it is - a detail is hanging loose that I noted to fix later. It bugs me, eats away at me like those worms that ate away Chekov's brain in one of the Star Trek movies. Six? Was that six?
So, I invented routines to get myself back on track and away from obsessing on the minor detail. I remind myself of priorities. The priority is to finish this round of revisions / spit and polish on the manuscript. I'm sure there are other minor errors I've missed. But, I can fix them later and it won't take long to do so.
Perfectionism is a hard thing to give up. It's important though. To make progress, move on and finish anything started, it's important. I learned that in other things I've accomplished. It applies here, too. It applies everywhere in my life. I can't obsess about one tiny cloud when the rest of the sky shimmers with rainbows. Sometimes it takes longer than others to talk myself out of staring at the cloud. I eventually manage to pry my fingers loose and let go.
Stuck? Mired in doubt? Bogged down in frustration? Make a plan to nudge yourself out of it. See the bigger picture. Concentrate on what's going right. You may have to try a lot of things before you find something that works. The effort will be rewarded in the end though.