PITTSBURGH — John Challis, a former high school athlete who inspired professional players with his battle against cancer, died at his parents' suburban Pittsburgh home on Tuesday. He was 18.

Challis made national headlines when he threw out the ceremonial first pitch at a Pittsburgh Pirates game against the New York Yankees in June, leaving his home team a motivational message on their message board.

"Have fun," he wrote to the Pirates. "It's the reason we play ball."

The 5-foot-5, 93-pound teenager was diagnosed with terminal cancer when he was 16. He spoke candidly about his initial fear of death and then his determination to achieve his goals before succumbing to the cancer that had spread to his liver, lungs and other parts of his body.

Most of those goals were achieved. He played with the Freedom Area High School football team, where he was a starter as a sophomore before becoming ill.

He met Pittsburgh Penguins' owner and Hall of Famer Mario Lemieux and quarterback of the Pittsburgh Steelers, Ben Roethlisberger.

In April, he fulfilled a dream to play on his high school's baseball team, coming in as a pinch-hitter and drawing cheers — even from the opposition — when he hit a single into right field.

In June, after graduating from Freedom Area High School, Challis got to take a last cruise with his family. He also set up a foundation to help high school students fighting terminal illnesses.

His only regret, he told reporters in the months before his death, was that he would not be able to get married and become a father.