She told the Washington Post: 'Age is nothing but a number'.
Ms Shepherd has impeccably toned 'six-pack' abs that are the marvel of her Baltimore fitness centre.
Her husband of 54 years, Collin Shepherd, says he 'has trouble keeping guys away from her'. The Shepherds live in Baltimore with their son, 53, and grandson, 14.
Over the past 18 years, Shepherd has run nine marathons and won two bodybuilding contests.
Shepherd said she wasn't always so fit. She was a 'couch potato' until she was 56 years old, when she and her older sister, Mildred, discovered their bodies had started going soft. She says Sylvester Stallone is her idol. Not exactly your typical grandmother.