Matt Damon’s no wuss.

That might have been truest 10 years ago, when the star was vigorously training for his role as a jacked-up rugby player for the film “Invictus.” Still, he had to reconsider all his assumptions about strength and persistence when he couldn’t keep up with an 8-year-old.

Damon was visiting Ethiopia with his nonprofit, Water.org, which brings clean water and sanitation to countries in need. To get a sense of the challenges people face just to procure potable water, he followed a little girl around for a day.

“I was in really good shape,” the actor told The Huffington Post on Monday. “And this little 8-year-old girl put me to shame carrying this jerry can of water up a hill. I literally couldn’t believe how strong she was.”

That’s when the water crisis hit home for Damon, who saw how the grueling task of collecting water ― considered a “low-status” task ― disproportionately fell on the shoulders of women and girls. The chore can mean trekking miles to the nearest well and carrying cumbersome jugs all the way home.

“I have four daughters. I can’t imagine them doing this,” Damon said of the physical labor that girls in the developing world have to endure. “But that’s what they have to do. They have no choice. Not having water isn’t a choice.”

Nathan Small Before her village in Kenya received a water pump, Elizabeth, 24, spent about four hours a day collecting water. She often carried her son on her back and 20 liters of water on her head. "It's taxing, hard labor," she said.

Worldwide, 663 million people don’t have access to clean water. To put that into perspective, more people own a cell phone than have potable water.

Women and girls spend about 200 million hours every day fetching water in developing countries, according to UNICEF. And when they spend so much time collecting water for the household, they miss out on education and work opportunities. They’re also more susceptible to developing serious physical ailments.

In the years since his visit to Ethiopia, Damon has seen the same story unfold over and over for other women and girls in developing countries. But he says he’s more hopeful than ever, partly due to the partnerships Water.org has developed.

The actor is now at the World Economic Forum in Davos, Switzerland, to kick off the third year of Water.org’s collaboration with Stella Artois. The beer company’s “Buy a Lady a Drink” campaign encourages customers to buy limited-edition chalices from Brazil, Cambodia or Uganda. The $13 purchase brings five years of clean water to one person.

Through sales and direct donations, Stella Artois has helped provide more than 800,000 people with clean water. That increased access alleviates health issues and helps end the cycle of poverty.

Nathan Small After Water.org installed a water pump in her village in Kenya, Elizabeth, 24, was able to focus on developing her work as a seamstress since she no longer had to spend four hours a day collecting water.

Water.org’s work has already made a difference. After the organization installed a water pump in a Kenyan village, for example, it changed the course of a young woman’s life.

Elizabeth, who is now 24 years old and a beneficiary of Water.org’s community programs, started sewing to earn money after her alcoholic father abandoned her family when she was 7. But as the years went by, she couldn’t even focus on her craft. She walked about four hours a day to collect water, often carrying her baby on her back and 20 liters of water on her head. Afterward, the water had to be boiled and cooled to ensure that no one got sick from drinking it.

“It’s taxing, hard labor,” Elizabeth said in a video interview with Water.org.

Now that her village has a water pump, Elizabeth can focus on building her business, working as a seamstress.

Damon points to such examples as proof that the water crisis can come to an end ― and soon.

“We can be the generation that ends the water crisis,” he said. “It’s solvable and we can solve it in our lifetime. We really can do it.”