From PEOPLE Magazine Click to enlarge
It takes a lot to rattle Ethan Zohn. Even after being diagnosed with Hodgkin's disease in April, the Survivor: Africa winner remained his usual chipper self, good-naturedly shrugging off the loss of his famous shaggy mane in May as he started chemotherapy. But in June, reeling from hours of seasickness-like nausea caused by his third biweekly chemo round, Zohn's spirit was finally broken. "It's the closest I've ever been to death. You're not just talking about it, it's real," says Zohn, 35, who bared his self-doubt one sleepless night in his weekly video diary chronicling his cancer battle: "Why me?"

But the depression was short-lived. Even in his weakened state, the answer came quickly to the soccer player, who had used his Survivor celebrity to spotlight causes like HIV/AIDS in Africa, and who decided to share his personal videos with PEOPLE.COM in order to educate the public about cancer. "Maybe I was put on this earth to help others and educate others," says Zohn, who's nearing the end of a three-month chemotherapy regimen aimed at knocking out his rare but highly treatable CD20-positive Hodgkin's lymphoma. The result: a recent body scan showed that the mango-size mass in his chest is shrinking. Says a relieved Zohn: "It's good news."

Especially to his anxious family, who had already lost one member to cancer. Growing up in Lexington, Mass., Zohn was just 14 when colorectal cancer claimed his father, Aaron. With his two older brothers already moved out of the house, Ethan's upbeat presence "really saved my life," says his mother, Rochelle, 68.

Saving lives was Zohn's goal when he used most of his $1 million Survivor prize to found the charity Grassroot Soccer and became a full-time philanthropist. In the seven years since, "he was never home more than three days at a time," notes his girlfriend, Jenna Morasca, 28. The winner of Survivor: The Amazon, Morasca has taken on a caregiver role again since moving into Zohn's one-bedroom Manhattan apartment this spring. "'Who can I help?' That's who he is," she says. "That's never going to change."

Already Zohn has spoken on behalf of Katie Couric's Stand Up to Cancer charity. "Every seven minutes a young adult is diagnosed," he says. "I want to be the megaphone for this generation and use this to change the world."

With only one more chemo treatment to go (possibly followed by radiation), says Zohn, "I see the light at the end of the tunnel." And he's running toward it: Zohn vows to race in the New York City Marathon Nov. 1. "In the beginning I was incredibly scared of dying," he says. "Now, I know I'm going to be okay."

To see Ethan Zohn's video diaries, go to people.com/zohn