Are you one of those who gets distracted easily? I'm one of the lucky ones who doesn't have ADHD or get easily distracted. That doesn't mean I don't get distracted. It just doesn't happen easily or frequently. So, what do I get distracted by? I think it might be easier to break this down to what I might do when a distraction enters the picture. Distractions can be unrelated to writing, although I have many things that distract me while writing. One of that might affect other writers, maybe the biggest even, is editing.
I don't mean editing once you've written your novel. I mean editing while you're writing. Me? Guilty for sure. This is one of my biggest distractions while I'm writing, especially when I get an idea for a change of something I've already written. It is hard for me to jot it down and not lose it. I try to use my Notes App on my phone, although there may be a better app I can use for writing. Sometimes I write it in my notebook, but I have so much written there it might get lost. What happens is I go back to make the change and end up finding other things to change. People suggest not editing while writing, but I haven't changed my process because it doesn't seem to affect my results.
Research is another distraction. While I try to get all my research done and out of the way before I begin, sometimes things either sneak in that I need to stop to research or I missed something. Now, I'm not sure we can label this as a distraction. It's more like a necessity. Sure, I could highlight it or tag it somehow to come back to fill in my research later, but interrupting my flow of writing irks me.