You know how important exercise is, as we grow older.
Here are a few suggestions. I start each morning by standing outside behind the house and, with a five kilo potato sack in each hand, extending my arms straight out to my sides and hold them there as long as I can.
After a few weeks I moved up to 10 kilo potato sacks, then 50 pound potato sacks and finally I got to where I could lift a 100 pound potato sack in each hand and hold my arms straight out for more than a full minute!
Next, I started putting a few potatoes IN the sacks, but I would caution you not to overdo it at this level