1. Do not rely on motivation to complete your work. Sure, you can rely on it when you're writing early, but it's finite. Instead, rely on habits and discipline. This is how:
Time block: Set a duration in your day where you will sit down and write your story. Don't try to correct the mistakes during the duration, try to just write and edit after. Try to increase the durations by whatever extra minutes you're comfortable with weekly (e.g. 10 minutes this week > 12 minutes next week)
Schedule: Somewhat connected to a time block, set a time in the day when you will sit down and write (e.g. 3:10-3:20 pm, write)
2. Break down tasks. Instead of "Complete this", a vague goal; try to make realistic and possible goals (e.g. 200 words daily)
3. When you're in writer's block, just write or make a deadline (I don't like this tip since it gives off the feeling writing is a task like schoolwork.)
4. Eliminate distractions. Exit your YouTube videos and Roblox games. Focus on one thing: writing more.