The Importance of Stamina

This was my first tournament in about a year. Before that, it had been another year or so and before that another year or so. At this tournament, I played a 700 rated player first round. It was a simple game, shown below:

During the second game, my stamina limit was reached and I crashed hard. I was playing against a 1950ish player. The game is below:

I resigned after my second crash. My third game was basically nothing but crashes. I will post it shortly.