For me, it's reading all the excited comments from my readers. The amount of enthusiasm and love they give is absolutely amazing to me!
The first episode Blue Star Rebellion's Chapter 2 was released today, and it involves little more than characters going from one place in a new spaceship, to another place in the same spaceship... with minimal dialogue. I wasn't expecting much in the way of comments at all for this one, since nothing actually happens. It just looks pretty. Turns out my readers had other ideas, especially the WEBTOON ones, because the comment section there has already ticked over into two pages.
I feel so lucky to have such enthusiastic readers, and they absolutely fuel me to keep making more.