I use to look down on those who rested or napped unless they had a hard core medical condition. Oh how wrong I was and the Universe humbled my ass. Thanks Adrenal Fatigue stage 3/4.
Now I know regular rest is a crucial part of my success recipe. The key is to rest before you are tired. Much like they tell you to drink water before your thirsty. Once your thirsty, your body is already dehydrated. Once you are tired, you are already worn out!