Brain damage near the end of 30 mile training run

A thought while on my 30-mile training run for the Black Hills Ultra Marathon 50 miler, Leadville Marathon, and Pikes Peak Marathon which are all part of my personal challenges for the upcoming summer when I turn 70 years old.
The rest of the story: https://www.youtube.com/watch?v=9vy3lvoW6CI&t=135s