For homeless people without access to menstrual hygiene products, getting a period is more than a monthly annoyance — it can be a desperate situation. Twenty-year-old Nadya Okamoto knows that firsthand. That's why she founded the non-profit PERIOD in 2014, when she was just 16. PERIOD has since grown into a global community, which has served some 400,000 periods. We speak to Nadya about her goals for the so-called 'Menstrual Movement,' why Gen Z is at the forefront of the change and how to get involved. Follow @periodmovement on Instagram and purchase Nadya's book "Period Power: A Manifesto for the Menstrual Movement."