I have been laying new roof tiles on my neighbor's house, we took 4 rows.
Now I know why I think he had little initiative, he has a pancreatic abscess, emphysema and abscesses on his liver.
First they have to find out why, also take everything with quitting smoking etc. I recommend vaping or smoking pipe, as a way, a lot of the problems of long-time smokers are a bit of withdrawal, habit, taste. Smoking pipe without taking lung puffs is a good start.
We needed to take many breaks, work at his pace, but we managed more than he had thought.