Even basic things like waking up and taking a shower required so much energy that it would knock the young Latvian out for 12-14 hours a day. The ability to run up and down the court was near impossible, and Porzingis withdrew from teammates because it was too difficult to even hold conversations with others.
The thoughts of your body failing are scary enough for anyone, but to add even more agony — Porzingis was in a new country, with a new language and culture. It was hard enough to explain the way he felt, much less try to describe the agony in another language.