Do it tired. Do it anyway.
One of the stories that really stuck out at me in the book Flourish, by Martin E. P. Seligman, was that of how snipers are trained by the government
It can take about twenty-four hours for a sniper to get into position. And then it can take another thirty-six hours to get off the shot. This means that snipers often haven’t slept for two days before they shoot. They’re dead tired.
Instead of medication to keep them awake, he goes on to say,
…you keep them up for three days and have them practice shooting when they are dead tired. That is, you teach snipers to deal with the negative state they’re in: to function well even in the presence of fatigue.
When you are feeling tired, push ahead. Do it anyway. Do it tired.
You may be surprised to realize that this too is temporary. It ebbs and flows. Don’t give in.