Senior exercise program:
Stand 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; then relax. Each day you'll find that you can hold this position just a bit longer.
After a couple of weeks, move up to 10 pound potato sacks. Eventually, try to get 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 that level).
After you feel confident at that level, put a potato in each of the sacks.