LONDON, ENGLAND - FEBRUARY 05: The Duchess of Cambridge competes against The Duke of Cambridge and Prince Harry during the Team Heads Together at a London Marathon Training Day at the Queen Elizabeth Olympic Park on February 5, 2017 in London, England. (Photo by Chris Jackson/Getty Images)
LONDON, ENGLAND - FEBRUARY 05: Catherine, Duchess of Cambridge, Prince Wiliam, Duke of Cambridge and Prince Harry attend a training day for the Heads Together team for the London Marathon at Olympic Park on February 5, 2017 in London, England. (Photo by Samir Hussein/Samir Hussein/WireImage)
LONDON, ENGLAND - FEBRUARY 05: Catherine, Duchess of Cambridge, Prince William, Duke of Cambridge and Prince Harry attend a training day for the Heads Together team for the London Marathon at Olympic Park on February 5, 2017 in London, England. (Photo by Karwai Tang/WireImage)
LONDON, ENGLAND - FEBRUARY 05: Catherine, Duchess of Cambridge, Prince Wiliam, Duke of Cambridge and Prince Harry take part in a race during a training day for the Heads Together team for the London Marathon at Olympic Park on February 5, 2017 in London, England. (Photo by Samir Hussein/Samir Hussein/WireImage)
LONDON, ENGLAND - FEBRUARY 05: Catherine, Duchess of Cambridge, Prince Wiliam, Duke of Cambridge and Prince Harry take part in a race during a training day for the Heads Together team for the London Marathon at Olympic Park on February 5, 2017 in London, England. (Photo by Samir Hussein/Samir Hussein/WireImage)
