There are these diaries with preformulated questions where your dad could write answers to. Most of these questions are cheesy, but that isn't important.

"Who was your first love?", "Where did you meet your wife?", "what was your dream job as a child?" that kind of thing.

I found them extremely interesting to read since people tend to write more than they say or would casually mention. I think it also helped the writer as it lessened the fear that things were left unsaid.

Otherwise if he enjoys his routine, maybe it is the most important thing to do right now.