If you're writing just a novel (or a short story, or somewhere inbetween), let the thing rest. Let it proof like bread. Don't touch it for an extended period of time. Not 48 hours, either-- a week, a month, six months, a year, a couple years. Then, and only then, come back to it when you feel compelled. Read it again, take notes, make a reverse outline, decide what works, what doesn't work, what you want to change, what you never want to change.
It needs the room to breathe, and for your brain to come back to it fresh. To detach from its creation and look at it objectively as a soft, airy round of dough just begging to be punched. So punch the air out of it. Mold it into something better.
For example, I have a fantasy dark academia I've been working on for over a year at this point. I wrote out the initial plot two years ago, hated it. Wrote out the first paragraph for FirstLinePit, and that stupid thing sat there for ages until I finally sat down and wrote out the entire first draft in 2024. And then I let it sit for a week, and went in and added things, made the ending longer with more details (I sort of rushed it), giving side characters names, y'know.
I made the error of querying it at that point. I got one personalised rejection that basically said "hey your plot is compelling but what the fuck is happening in your sample pages." And she was right. So I reworked it, again and again and again--
I'm here to tell you: don't do this.
I eventually got the message that first drafts are ass, and I can do better. I rewrote it a couple months later, but didn't make it all the way through. And it was sitting, untouched, until last month. I wrote a reverse outline. I printed it out. I read through that outline and wrote down notes for myself. I changed around a certain plot point I hated and added nothing.
Am I writing it now? No. It's sitting in my plots binder, mocking me. It's going to be this long-ass chore to rewrite the entire thing, basically writing it again from scratch. Am I excited to write it? Yes. Immensely. There's something about this story and this world that draws me back in, the characters, the tension, the drama, the politics, the use of journalism as rebellion--!!
But I'm not ready yet. So I'm writing other stuff. Stupider stuff. First drafts and query letters and my stupid, stupid glee chunni romantasy with an ancient vampire who's dad is the god of Death and the MC is an enby heir to the metaphorical throne of violence, destruction, and blood that her grandfather wreaked upon the world. It's stupid. And that's the point.
You don't get in the millions of words written by writing really good shit; you write the stupid stuff. You learn the craft, you write fanfiction to learn to work within world canon and with created characters, you write smut (if you're into it) so you can get into the stupid and weird with no plot required so you can just write it.
I have literally millions of words that will never see the light of day, just like artists have thousands upon thousands of scrapped files, pages, sketchbooks, smudged charcoal, painted over canvasses, doodles-- it's a craft.
Take the first steps in whatever brings you happiness. I personally love serials-- wrote one for a paranormal forum I was on ages ago. Having a deadline definitely helps with motivation. Just don't push yourself.
Which is why my serial on here hasn't been updated (though I've written more). I got overwhelmed, and that's okay.