It does take a while to get there - but if you're maxed out on Medecine, he'll probably survive long enough - but that also depends on the difficulty level you're playing at. My current game is "Normal", and my villagers tend to die in their late 80s. Take a look at your stats and see what age your oldest villager is / was.

If nobody else volunteers to help him, try dragging someone over (if they even have the tiniest bit of expertise, they should get stuck in).

As for taking breaks, how would you feel if you were 67 and were made to dig all day, every day?

Good Luck.