When you are fatigued making so many decisions day after day hour after hour all day and then doing the same when you go home at night. Its impossible for you to be your best.
I used to laugh when I meet someone new, and they asked what I did for a living. “I own and operate a spa.” I would say. Then I'd wait for it. “Oh! That must be such a relaxing job!” they would reply, eyes bright and imagining working in a candle-lit room, listening to spa music and giving a facial. Yes, that sounds like it would be an amazing career! LOL. Nothing could be further than the truth though.