For those of us getting along in years, here is a little secret for building your arm and shoulder muscles. You might want to adopt this regimen!
Three days a week works well. Begin by standing outside behind the house, and with a 5-lb. Potato sack in each hand, extend your arms straight out to your sides and hold them there as long as you can.
After a few weeks, move up to 10-lb. potato sacks and then 50-lb.potato sacks, and finally 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.
Next, start putting a few potatoes in the sacks, but be careful not to overdo it at this level.