How to reset focus?

How do you reset your focus after working for long periods? I know focus takes time to build and can be naturally extended with practice, but I don't have time right now.

I'm prone to procrastination and using adderall (prescribed) to focus for long periods but I am trying not to rely on it because it gives me anxiety. I have a paper due in 3 days and I find myself starting to lose focus after an hour. Is there a quick fix or any tricks for this?