Don't be fooled. It can be hard to impose limits, and it's no different with writing. That's why tip #94 is to set a word count limit.
This can vary from assignment, but by setting limits it forces your mind and body to take a break. Get up and take a ten minute walk, switch to a new task, or eat a snack. It will leave you refreshed and focused on the writing ahead.
It may seem counter intuitive, but try to stop mid-thought. This way when you come back to the assignment, you'll have a clear idea of what to write next. By putting limits on your word count, you keep the task small. This can help you avoid burnout and keep you energized throughout the workday.
If you're not convinced, consider Hemingway's words:
"I had learned already never to empty the well of my writing, but always to stop when there was still something there in the deep part of the well, and let it refill at night from the springs that fed it."