Well as someone who writes novels for amazon, and does the writing for my webcomic. It's kind of interesting.
Honestly, I'd be lying if I said the payoff wasn't a part of it. My novels are like a 1/4 of my income for the month now. So I can't really stop writing them without a bit of a penalty.
But usually, it's the first 2-3 chapters that are the hardest to write. Getting over if the idea is good enough to create, and people will like.
As for scenes, sometimes I just have to brute force things. Maybe use Grammarly to help me a little find better wording for certain scenes ect.
Worse comes to worst, I'll fix it during the editing phase. Since I usually only do 2 drafts of my novels.