There are many different things that motivate people to write. Maybe it’s just getting views or likes on your story. Others find feedback and comments on their story very motivating. Some even find the motivation to write in just really enjoying their own story!
What is it that motivates you to write?
Reading other people’s stories 
Having a clear goal/idea in mind. Having writers block would usually stop me from writing for a couple of days. Also being focused and not getting too many hate comments.
Just having a story to tell, I guess. I don’t write just for the sake of being a writer, I do it because I love creating characters and expressing their experiences.