Gentle weightlifting for the over-50s

I heard about an easy weightlifting exercise for older people, to help build and maintain muscle strength in the arms and shoulders. It seems so easy, so I thought I'd pass it on.  Recommended as a 3-day/wk regime.

Begin by standing on a comfortable surface, where you have plenty of room at each side. With a 5kg 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 for just a bit longer. After a couple of weeks, move up to 10kg potato sacks. (I'm at this level now).

Then try 50kg potato sacks and then eventually try to get to where you can lift a 100kg potato sack in each hand and hold your arm straight for more than a full minute.

After you feel confident at that level, put a potato in each of the sacks.