I started a cancer nonprofit at 14 after losing my grandfather and teacher. Now it has 40,000 youth volunteers.

Olivia Zhang started her nonprofit at 14. Courtesy of Olivia Zhang Olivia Zhang founded Cancer Kids First after losing her grandfather and teacher to cancer. At first her immigrant parents didn't understand her desire to lead a charity, she says. Now, she's a junior at Harvard teaching other young people how to become leaders. This as-told-to essay is based on a conversation with Olivia Zhang, author of "YOUth: The Young Person's Guide to Starting a Nonprofit." It has been edited for length...