Here is a great article on what it means to pace yourself, take it easy, and not become engaged in uninteresting ideas. A simple walk can do you so much good.
A brief aside: I have to be honest with you. Sometimes I fail at walking as a break. I come to a point where I ask: Okay, if I'm going to take a walk, where will I go? What will I do? What is the purpose? It becomes a stress of its own. How can I engage and let go when I treat relaxing as another type of work I need to commit to? Maybe I'm the only one who has thoughts like this.
As a side note, the article also reminded me of a patent by Apple on how they designed the MacBook indicator to work at the rate of a human breath when it is sleeping.