"The main challenge is technology and that's something I really push and work closely with Adidas on. They're real leaders in sports performance; always trying to push that further and further and get the best technology they can. That takes time and has rigorous testing, it's very laborious, but it's also very rewarding. You get to work with fantastic athletes, and that's a fantastic thing that has nothing to do with my day job in ready-to-wear."