"There's nothing I'd rather be doing with my life," the young doctor says. "Absolutely nothing.
And it's a hard life: seven-day work weeks, including house calls. And a house call in Haiti can mean a hike up the side of a mountain.
"You walk for 30 minutes, walk for an hour, walk for four hours. The patients do it every day, why shouldn't I do it?" Walton explains.
On the day 60 Minutes was there, Walton was visiting 10-year-old Cledene, who is suffering from a damaged heart valve. Her family and neighbors showed up with their list of ailments. There are no short lines in Haiti. Some of Cledene's siblings were also sick from sleeping on a muddy floor. Including the parents, 12 people sleep in one room.
"In the scheme of poverty in rural Haiti, this is pretty bad around the lower end of the spectrum, 10 kids living in a place like this, no material possessions and a very, very sick child," Walton remarks.
Even for the well-trained this is difficult. "I can't imagine, sorry, turning my back on something like this," Walton says. "Maybe some people can, but I can't and I won't. This is my life's work."
There was no happy ending for this story. Cledene died not long after Dr. Walton's house call.
"There are always whispers about programs like this that they can't outlive the people that founded the place. That when the Paul Farmers move on, Partners In Health will be done," Pitts says.
"Paul, part of his genius is that he has set up a system that doesn't depend on his presence or absence. Haiti is run by Haitians physicians. In Rwanda the Rwandan hospitals should be run by Rwandan physicians," Walton says. "And so when the Paul Farmers of the world aren't around anymore, this place will still be here providing great care."
Asked if he knows that or just hopes that, Walton says, "I know it."
But there's no question that Farmer has been a driving force. Take AIDS, for example: in the late 1990s the disease was ravaging the people of Haiti. Conventional medical wisdom was there is no point in giving AIDS drugs to the poor in Third World countries. But Farmer wouldn't give up on his patients. He raised money and gave them drugs anyway.
Patients, like a man named Joseph, went from being very ill to feeling better. The same kind of transformation happened in patient after patient.
"When Paul started treating people in 1998 in Haiti, everyone said he was absolutely nuts. 'Impossible. Can't be done. Forget about it,'" says Dr. Jim Kim, a professor at Harvard Medical School and one of the co-founders of Partners In Health.
"And here we are, you know, not even a decade later, where the goal is to treat every single human on the planet who needs HIV treatment with the right drugs," Dr. Kim says.