The Duke & Duchess Of Cambridge And Prince Harry Outline Plans For Heads Together Ahead Of The 2017 Virgin Money London Marathon [Getty Images]

LONDON, ENGLAND - JANUARY 17: Catherine, Duchess of Cambridge, Prince Harry and Prince William, Duke of Cambridge arrive for a briefing to announce plans for Heads Together ahead of the 2017 Virgin Money London Marathon at ICA on January 17, 2017 in London, England. Heads Together, Charity of the Year 2017, is led by The Duke & Duchess of Cambridge and Prince Harry in partnership with leading mental health charities. (Photo by Karwai Tang/WireImage)

WireImage Karwai Tang