"If you don't see it as a problem, then it's not a problem," Quinn tells PEOPLE
Credit: Courtesy of St. Francis High School

It’s a storybook ending to a phenomenal season: Riley Quinn makes the final tackle of the championship game, thwarting a potential winning touchdown by the opposition.

Impressive for any high school varsity player, but even more so for the San Francisco Bay Area native Quinn, 18, who was born without a hand and forearm as a result of an amniotic band breaking free and wrapping around the developing arm early in the pregnancy.

“Riley’s an athlete, he’s a football player,” his coach Greg Calcagno tells PEOPLE. “He isn’t a kid with a handicap who is on our team, he’s a two-year starter and a captain. He’s one of our best football players.”

Sporting a varsity letterman’s jacket that spells out his unique triple-threat status in football, basketball and baseball, the honors student carries himself with confidence and smiles easily and often.

“My philosophy is that if you see the world as a bad place, it probably will be,” Quinn says. “But if you go in with good attitude and are lucky enough, like I am, to have the love and support of family and friends, then it’s all going to be all right.”

Quinn tells PEOPLE that he goes months at a time forgetting he only has one hand on the arm he calls “Marty.” He pops a superhero cape on Marty prior to game day as a good-luck charm.

“If you don’t see it as a problem, then it’s not a problem,” he explains. “Practice, be creative and it will be okay.”

Quinn says there’s no doubt he’s a better player because of his disability rather than in spite of it.

“I definitely go into this with something to prove – I have to outwork everyone else to make up for it,” he says. “I’m a natural athlete, so that helped especially when I first started playing. I never played in handicapped leagues. But as the competition got stiffer, I just had to want it more than anyone else.”

“If I’m good enough, I deserve to be on the team. Every time I faced a challenge, I said to myself, ‘Okay, that was hard, but I just need to overcome it and do it.’ ”

“It’s his will that sets him apart,” adds baseball coach Mike Oakland. “He’s our best fielding pitcher and he makes our players want to play harder and perform better.”

His basketball coach Mike Motil tells PEOPLE, “Every day he brings a level of competitiveness that is inspiring to the entire team. He has that attitude of ‘just tell me I can’t do it and I’ll prove you wrong.’ He processes information quickly and is a mentally and athletically gifted kid. But it’s his work ethic that really sets him apart.”

One of Quinn’s inspirations came when he was 10 and met Jim Abbott on the golf course. Abbott, who was born without a right hand, played major league baseball from 1989 to 1999.

Now it’s Quinn’s turn to become an inspiration to others. After a recent football game, young Emma, 8, who has a similar birth defect, wanted to meet him after a game. The chance to come face-to-face with the girl left them both moved, and the two shared a “nub bump.”

“I never thought about being an inspiration to other people, but if I can be I think that would be great,” says Quinn, who just received an offer of a full football scholarship from University of San Diego and a walk-on offer from Yale University. “I used to say my biggest frustration was that I couldn’t go on the monkey bars. But now I can. I just needed to get bigger and stronger.”