Taking a break is important, not only for the rest, but also for the re-fueling. You cant’ re-fuel a car while zooming down the highway at 80mph (at least not yet). You also cannot increase your appetite while stuffing your face full of donuts (as much as I try). Humans are the same way. We must reach a state of rest before we can re-fuel. We must go without for a while in order for the hunger to grow.
Now, there is a caution here. You can use your break, or you can abuse your break.
For the bum, a break is nothing more than an excuse to get out of working for a certain period of time.
For the artist, it is a vital tool she uses to increase her appetite for the work, to add fuel to her fire whenever she feels is burning dim.