Begin by standing on a comfortable surface, where you have plenty of room. Extend your arms straight out from your sides and hold a 5 lb. potato sack in each hand. Hold as long as you can. Try to reach a full minute. Relax. Each day you should be able to hold it a little longer. After a couple of weeks, move up to a 10 lb. sack. Then, when you're comfortable, go to a 50 lb. sack. Eventually you may move on to a 100 lb. sack (this is the level I'm at). After you feel comfortable at that level, put a potato in each of the sacks.