It just kind of happens. I put in music, follow my outline, and put the vision in my head to paper. I do get distracted a lot by YouTube, memes, people, and life in general but when I'm writing, I immerse myself in what I'm doing until I hit a point in the episode where I can call it good.
Edit: Just to add, word count is mostly related to having a supportive vocabulary that allows you to be descriptive. You can write a good story with a low word count. If you want to change that and fluff your numbers, the general issue I've noticed is that the author doesn't have the diversity in their word bank to bring out what they want to say.
Read more. Write more. It'll come.