Helen Clark of Kennebunk, Maine, is a smuggler of sorts. At 77, the retired registered nurse doesn't look the part. She still does volunteer work--administering flu shots, cutting toenails and organizing blood drives--at the Southern Maine Medical Center, where she worked for more than four decades, first in the maternity ward and later in the operating room.
Clark is a model of frugality as well. She and her husband Dorrance raised 10 children on modest salaries. When he developed lung cancer in 1991, she stopped working to care for him until he died. She has lived in the same house since...