At 15 Kelly was diagnosed with a rare and aggressive form of cancer in her right knee. Faced with the option of amputation or radical surgery to remove the cancer, Kelly chose amputation for her best chance of survival. This decision would change the direction of her life. After months of painstaking rehabilitation and learning to walk again she looked for a new direction. That direction was running.
Kelly raised enough money to purchase a purpose built running leg and after training 6-7 days a week soon became Australia's best above-knee amputee sprinter. With a growing passion for running and her determination Kelly decided she wanted to be the best 100m sprinter in the world. In 2011 Kelly competed in the World Championships and returned with two gold medals and a new world record in long jump. 2012 was by far her biggest year and with her previous performances was under pressure at the 2012 Paralympic Games in London. Drawing on all her training, she rose to the top in Long Jump, setting a new world record; claimed the gold medal; and ran a personal best in the 100m to claim silver.
Away from the track, in 2009, Kelly became the first above-knee amputee woman to climb to the summit of Mt Kilimanjaro.