I recently came across this exercise suggested for older adults, to build muscle strength in the arms and shoulders. It seems so easy, so I thought I'd pass it on to some of my friends.

The article suggested doing it three days a week. Begin by standing on a comfortable surface, where you have plenty of room at each side. With a 5-lb
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'll find that you can hold this position for just a bit longer. After a couple of weeks, move up to 10-lb potato sacks.

Then try 50-lb potato sacks and then eventually try to get to where you can lift a 100-lb 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