I used to be one of those folks who believed, in an entirely American way, that taking time off was for the weak.
I reveled in the fact that I could "push through" or "battle on" and made sure everyone knew that even if I were physically out of the office, I wasn't actually OUT—I was still checking and responding to email, available for phone calls, and generally plugged in. I treated it as a sign of strength and fortitude and dedication to my work that I never needed to take a break.
I was an idiot.
This is an idiotic way to look at things. It's toxic, and it prevents more than a few people from being able to admit when they need a break, and from being truly excellent at what they do.
No one can work constantly and be any good at it. The human brain needs time to rest, to think deeply, and to reset. No matter how much you love your work, no matter how good you are at it, if you stay on the treadmill of "doing things" forever, your work quality will slip, right alongside your life quality.
I'm ashamed to admit that it took me until my late thirties to realize the pleasure, and necessity of a completely unplugged break. I wonder how much better I could have been at everything earlier in life if I'd just...stopped...every once in a while and taken a breather. Water under the bridge, I know, but now that I understand how important taking true time off is, I build it into my schedule every quarter. A long weekend spent in nature, reading fiction and taking long walks makes me a better business owner/consultant/wife/mother than "pushing through" ever could.