How would you feel if your personal trainer was twice your age? With 78-year-old Ernestine Shepherd, you'd probably be motivated to finish that last set of bicep curls. In 2011 when she was 74, Shepherd was the world's oldest female bodybuilder, according to the Guinness Book of World Records. She also works as a certified personal trainer at her Baltimore gym, and wakes up at 3 a.m. every morning to run (she logs 80 miles a week) and lift weights (she can bench-press 150 pounds). "I feel better than I did at 40," she told ABC News.