Boxer / 30
When you’re watching Mary Spencer, the three-time world champion boxer, it’s all about the rapid jab to the head, chased by a sharp left hook to the ribs, which knocks her opponent to the ground. Spencer grew up on a reserve in Southwestern Ontario. She started boxing at age 17—her future coach, Charlie Stewart, heard that she was beating up boys at school and offered her a more productive outlet for her strength. She starts her training every day at 6 a.m. with a seven-kilometre run, followed by sparring sessions and strength training. This summer, she’ll be defending her middleweight championship at the Pan American Games in Toronto, but that’s just a warm-up for Rio in 2016. It’ll be her second trip to the Olympics—she placed fifth at London 2012. This time, she doesn’t plan on leaving without the gold.