Some people become activists by necessity. Others, by chance. Nineteen-year-old Robyn Hamlyn stumbled into her cause—and then dove in, headfirst.

A water campaigner from Kingston, Ontario—one of the most water-rich regions on the planet—Robyn originally discovered her passion thanks to her teacher’s sick day. It was the last class of an otherwise unmemorable Grade 7 day in 2011 and Robyn’s supply teacher, whiling away the final minutes before the bell, showed the class a documentary. As the rest of the class watched the clock tick, Robyn watched Blue Gold: World Water Wars and was transfixed.

“I ran out of the classroom and all the way home,” she says with an unselfconscious laugh. “I knew I had to do something. I wasn’t sure what yet, but I just felt it.”

I sat down with Robyn backstage at last year’s WE Day Toronto, just after she had shared what came next with 18,000 young change-makers. Their energy was still coursing through her as we spoke. She told me what it was like being a 12-year-old with a dream, and how she had taken her first furtive steps into the world of activism before finding her stroke. By swimming against the current, her story shows just how much one determined person can accomplish.

The documentary Robyn watched those many years ago had shown her a world with a dwindling water supply, pillaged by corporations and fought over by nations; a frightening and confusing scene for a girl who lived near the banks of Lake Ontario. So, on her mother’s advice, she wrote to Kingston’s mayor saying that just because Canada is a waterlogged country with 20 per cent of the planet’s supply, that doesn’t mean water crises can’t happen here.

Two weeks after writing to the mayor, she came home to a message on her answering machine. He wanted to meet.

“It was one of the best moments of my life,” she recalls energetically. “But I realized I couldn’t go in there and just say ‘I’m scared.’ I couldn’t let him just tell me to take shorter showers. I had to come up with a plan.”

Robyn looked to those already engaged in water activism and, taking a page out of The Council of Canadians playbook, decided to ask the mayor to make Kingston a Blue Community. The designation has three components: banning the sale of bottled water in city facilities, supporting public ownership of water and recognizing water as a human right. The mayor committed to taking her idea to council—and he asked Robyn if she’d present it.

Robyn spoke in from of Kingston’s City Council in September 2011, holding court for 15 minutes, sharing stats and stories about the impact of the water crises. By the end of the session, they had voted to recognize water as a human right and began promoting publicly owned and operated water services, two of the three steps to becoming a Blue Community.

Robyn was elated, but not satisfied.

“I realized how powerful one person can be,” Robyn says, recalling the day. She expanded her activism into other realms, helping collect water samples of the Great Lakes to test pollution levels. And she set a goal to make every town and city in Canada a Blue Community. She started by sending letters to mayors across Ontario. The response was incredible. She remembers getting a call early one Saturday morning while she was still in her pajamas from the mayor of Ajax, excitedly telling her the city council would discuss her ideas that week. Since then, she’s spoken in front of dozens of city councils and inspired seven communities to go blue.

But more importantly, she’s branched out beyond the halls of power, bringing her message directly to young people. “As strong as one person is, we’re stronger together,” she says, absentmindedly fiddling with a reusable water bottle. “This is our future and I believe we deserve to know what’s happening and be given the chance to do something about it.”

Robyn discovered this issue by accident, but she’s not taking that chance with others. She’s spoken at dozens of schools and launched Water Warriors, a website full of information and suggestions on how to take action. She’s also reached out to schools to help make water scarcity a part of the science curriculum, relying on resources she’s assembled to ensure those impacted by the issue are equipped to deal with it.

Her dream of inspiring young people is what brought her to the WE Day stage. There, she got a chance to mobilize an army of water warriors to help protect Canada’s water. As her speech reached a crescendo, she ended with one final rallying cry: “This is our water, and it’s our future,” she told the raucous crowd. “It’s up to us to save it.”