One of the strange things he noticed ( besides wasting from 165 pounds to about 120 ) was that while his strength stayed intact, his endurance went down to nearly nothing.
In those days, it was a "you kill it, or it kills you" proposition.
Back before isoniazid, it really was a "wait it out" proposition. I'm glad your daddy beat it before it beat him.
Exhaustion is one of the first symptoms - can't lift your head off the pillow type exhaustion.