Possible job for a 69 year old retired teacher?

My father retired from teaching in the mid-90’s. To supplement his pension (and now, his social security), he took on a string of retail jobs including Store Manager, Inventory Manager, and Sales Associate.

The problem with his job now is that it is too physically demanding of a 69 year old man. He is on his feet all day and sometimes has to lift heavy materials.

I’m starting to look on various job sites for a new job for him, but I figured I would ask for suggestions first.

Here are the facts:
-Retired English Teacher (Degree in English & Master’s in History)
-Former Marine
-Hobbies include writing, photography, & home improvement.

Until my parents sell their home, he will need to make what he is making now which is around $2,000/month net.

Any ideas?