Meet one of the world's toughest grandmas - an international powerlifting champ who says she looks and feels better than she did 30 years ago. Mary Duffy, 71, took up gym work outs at 59 in a bid to lose weight, and soon got hooked on lifting weights. Now she spends around 20 hours a week pumping iron and exercising, and has more than 30 state and world records to her name.