I don't know about you, but I feel like I've been working non-stop for years now, and I don't know how I'm able to do it. And it's often because I include activities in my daily life that make my work more enjoyable or break up the monotony.
For example:
I exercise every day (and listen to video casts about tech, business, and marketing in the background)
Yesterday, in a few Reddit forums and generally from the discussions around me, I noticed that people are "tired" of office work.
Either too much routine or exaggerated demands on creativity and the like. Mostly, these are people who are paid well and can afford to "leave" their jobs to explore, relax, do something else.