UNITED NATIONS (AP) — Pakistani teenager Malala Yousafzai, who was shot by the Taliban for campaigning for girls’ education, told more than 500 young people Monday that they should start working right now to change the world.

The 17-year-old said raising her voice helped bring a change for girls who were not allowed to go to school in Pakistan’s troubled Swat valley where she lived until she was shot. Malala spoke at an event to launch 500 days of action to achieve the U.N. Millennium Development Goals to fight poverty, which include ensuring that every child has a primary school education.