Once you have become strong enough to one-arm swing the Simple kettlebell for 10x10 with the talk test, the five-minute swing test, and practicing for it, will provide difficulties in spades. Meanwhile, challenge yourself once or twice a month in a variety of ways. Help a friend move. Shovel snow for the entire block. Take out your dusty boxing gloves and call up your old sparring partners. Run up a mountain with a backpack. Enter a 10K race. Farmer-carry your kettlebells for distance. Take on any physical challenge that will test your spirit without breaking your body.
