By Lauren Said-MoorhouseInes Torre and Matthew Ponsford, for CNN

Today is International Day of the Girl – a date set aside to advocate for girls’ rights and raise issues of gender bias.

CNN spoke to some of the world’s most remarkable and impressive women – from across the fields of politics, science, media, sports and culture – to find out: “Looking back, what one piece of advice would you give to your 15-year-old self?”