06/18/2007 at 01:00 AM EDT
wasn't exactly sure he was qualified to be a high school graduation speaker. "I'm sure many of you could school me on that [Are You] Smarter Than a Fifth Grader
show," Affleck joked as he addressed Falls Church (Va.) High School's Class of 2007. Better to leave the praise to graduating senior Joe Kindregan, who, from his wheelchair onstage, introduced the star speaker as "an award-winning actor, married to the cutest girl, and he's a great dad. Most importantly, he's the best friend you could ever have."
Affleck's friendship with Kindregan, 19, goes back almost a decade. In 1998, Kindregan visited the set of Forces of Nature
, which was filming at nearby Dulles Airport. Kindregan, who has ataxia telangiectasia (AT)—a degenerative disease that causes loss of muscle control, cancer and immune-system failure—"wasn't like other kids," Affleck told the audience. "He was on a mission." Enlisting Affleck's help in his drive to raise research funds to find a cure (people with AT rarely survive their 20s), Kindregan "made it to the set of every single movie I ever made," said Affleck, 34. "If that were me, because I am not as strong as my friend, I think I would have had a much harder time fighting uphill.... Everything that I learned about life that matters, I learned from my friend."
Kindregan's special day didn't end there, as Affleck and wife Jennifer Garner
joined Joe's family and friends for his graduation party—a green-and-gold-themed (his school colors) barbecue. "This was a big milestone for Joe and a big celebration," says his mom, Suzi. "He was very happy to share his friends Ben and Jen. Joe said it was the best day of his life."
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