Sunday's frigid weather was no hurdle for the more than 200 people -- old friends and new -- who took on Nate's Knockout Challenge, where the goal was a lot larger than finishing the obstacle course.

Westport native Nate Greenberg is a 21-year old senior at Union College who was recently diagnosed with Ewing Sarcoma -- a rare bone cancer that largely affects teenagers and young adults. In a show of support--and in an effort to raise funds for research -- the Knockout Challenge staged at Staples High School drew entrants from across the tri-state area.

"It's amazing," said Greenberg, the senior captain of Union's lacrosse team, who was also a lacrosse and soccer standout at Staples. "It's incredible. I'm at a loss for words."

"This is just such incredible support from the community," he said. "It just goes to show what a community can do when someone's in need."

"We wanted to do something to honor and support him," said Rich Bobrow, president of the Westport Lacrosse Association, who helped organize the event. He credited local volunteer support that made the challenge possible, including The Fitness Factory, which organized the athletic endurance course on the Staples football field.

"I would say there's at least 200 here today," said Roni Goldberg, a parent who helped get the event organized in a short timeframe so it would not interfere with Greenberg's treatment schedule.

"Nate was a huge part of the Lacrosse Association here and we're like a family," she said.

Goldberg said organizers hoped to raise more than $20,000 from the event, which will be donated to Memorial Sloan-Kettering Cancer Center for research into Ewing Sarcoma.

"There's so much love and support," said Greenberg's older sister, Leah Brandfon.

"It's really heart-warming," she said. "It makes me feel so good to see all this love."

But Knockout participants downplayed the importance of their involvement.

"For us to do something like this is not so big, compared to what he's doing," said Michael Miceli of New Rochelle, N.Y., a friend of Greenberg's from Union College.

"The whole thing has been really inspiring," said Allie Silvershein of Warren, N.J., who has been dating Greenberg for the past year.

"He's been amazing," she said. "He's been so positive."

"He's the greatest kid I've ever met," said Rob Santangelo of Rye, N.Y., who has been Greenberg's roommate since freshman year at college.

"He's always happy, always has a smile on his face, and he's stronger than most people I've met in my life."

"I feel great," said Greenberg, moved by the show of support. "I'm feeling good."