When In Doubt
When in doubt about whether you should work on something else or go for a walk, always choose the second. If you have a dog, take it with you.
Why? Because the time you will spend on this break will give you the needed energy to complete the task you wanted to do in a lot less time. Plus I don't have to preach you about the benefits of a bit of exercise.
What are you waiting for, go for that walk and clear your head for a few minutes.