As you will see, Pat Cunneen understands the progressive resistance exercise concept. His plan follows:
Easy Exercise for People Over 70
(You do not need expensive equipment)
Begin by standing on a comfortable surface, where you have plenty of room at each side.
With a 5 pound potato sack in each hand, extend your arms straight out from your sides and hold them there as long as you can. Try to reach a full minute and then relax. Each day you will find that you can hold this position for just a bit longer.
After a couple of weeks, move up to 10 pound potato sacks, then try 50 pound potato sacks, then eventually try to get to where you can lift a 100 pound potato sack in each hand and hold your arms straight for more than a full minute. (I'm at this level.)
After you feel confident at that level, put a potato in each of the sacks.
On the serious side, Pat, in his seventies, still competes in triathlons.