 A swimming coach advised her to concentrate on running because there were already several top swimmers in the Netherlands at that time (such as Rie Mastenbroek), and she would have a better chance to qualify for the Olympics in a track event.Her first appearance in the sport was in 1935, aged 17.Her first competition was a disappointment, but in her third race, she set a national record in the 800 m. Fanny Koen soon made the Dutch team, although as a sprinter, not a middle distance runner.