I guess there are two ways you can deal with breaking in your graduate studies. You can take a break or the work can break you. Either way, the intensity of your endeavor will force you to stop at some point if you don't plan in stops along the way.
I know several people who never get sick. Sorta. They don't get sick for long periods of time and then when they have a break (vacation, holidays off work, etc.) they get very, very sick. The doctoral experience can do the same thing. If you don't schedule in time to rest and relax, your body will force you to.
Here is a good article about thinking (and planning and DOING - thinking is not enough in this case!) about how to incorporate breaks and boundaries in your experience. https://www.insidehighered.com/blogs/gradhacker/i-need-some-space
