Proper exercise for Seniors

Dear Maude,

I'll be 75 next week and I want to stay in shape
when I get old. Can you suggest some exercises
that will help me stay fit and trim?
Thank you,
Sagging in Saginaw

Dear Sagging,
Start by lifting a 5 lb potato sack. 10 reps three times a week.
After two weeks, move to a 10 lb potato sack. Same routine.
After two more weeks, move to a 25 lb potato sack.  Same routine.
Then, after two more weeks put a potato in each sack.