Heidi began her athletic career at Cherrybrook Little Athletics Club, where she showed early promise in the middle and longer
distance events. Heidi first competed for Hills at the age of 14 under the tutelage of coach Grant Cremer, and soon began dominating her
training partners as well as much older rivals.
However, it wasn't until late 2004 that Heidi began to turn heads at the track. In February 2005, Heidi's smashed her 1500 metre personal best time
with a 4:20.30, a world youth qualifying time. Within the space of a few weeks, Heidi ran a second world championship qualifier, a 4:25,
to secure her position on the Australian Team for the World Youth Championships, where she would later finish in seventh place against a field of
older and more experienced elite athletes.