I would like to comment here as well. First, I do not do this. I am a writer but my partner, pony does. I suppose I am more like a friend and supporter of artists. I feel it makes me a little more objective.
The point here, in my humble opinion, is balance and taking care of your body. Such as eyes, spine, brain, and parts like that. If you do not take care of them one day they will stop working for you and then you really will be up the proverbial creek. LOL
Also fatigue causes confusion and clouded thinking. Learn where that line is for you so you know when you are crossing it and can get away from your work. Take a much deserved break and return a while later refreshed and ready for more.
Hope I do not sound too much like a "mom" here....LOL
"Si vis pacem para bellum" if you desire peace, prepare for war.