In this opening clip from CNN’s “Tech For Good,†Kristie Lu Stout speaks with South African surfer and swimmer Caleb Swanepoel, who was back in the water just three weeks after losing his leg in a shark attack, with the help of a state-of-the-art prosthetic limb. Designed by German company Ottobock, the prosthetic is computerized and uses sensors to mimic a natural gait – allowing Swanepoel to continue doing what he loves most, and even compete in international championships.