Pushing past the point of focus only leads to diminishing returns, anyway. It’s as though you are pouring and pouring, but all that extra water is just going to waste, and in fact giving you something you now have to clean up.
Sometimes, it feels like discipline means treating yourself like a drill segreant and not taking no for an answer.
But sometimes, discipline means having the courage to say, “This is what my best looks like right now, and that is enough.” Another opportunity to work will come. We all have limits, and there is no prize at the end of life for forcing your way through yours. Pace yourself. Take time to digest.