When Griffin Kushen was leading the freshman basketball team in scoring at Tesoro High, he was certain about his future.

“Basketball was my life,” he said.

He was a shooting guard who had played club basketball since he was 9. Two older brothers had been cross-country and track athletes at Tesoro, so his parents kept nagging him to stay open-minded.

“I was really anti-cross-country and anti-running,” he said.

He still went out for cross-country and track to please his parents. And something magical happened — he was good at it.

“I was all basketball,” he said. “As I got better in running, the team environment drew me in and the competitiveness. I found something in the sport of running that was never there in basketball. Don’t get me wrong. Basketball has been my sport for so long.”

Kushen became such an elite runner that he’s headed to a basketball school — Duke — to run cross-country and track.

Tesoro’s Griffin Kushen gave up basketball to focus on running.

(Gina Ferazzi/Los Angeles Times)

“I’ll get to see some great games,” he said.

He won the Southern Section Division 2 championship in cross-country in the fall, was second at the state championships and on Saturday is set to run in a mile race at the Arcadia Invitational that includes New Zealand high school phenom Sam Ruthe, who ran 3 minutes 58.35 seconds last month.

“Winning an Arcadia race is something special, the most prestigious race in America,” Kushen said.

At almost 6 feet tall and getting all A’s on his report card, Kushen recognized there were other avenues to college besides basketball.

“I realized it’s so competitive in California,” he said. “It’s a great basketball state. The chances of going far is tough. It was a really difficult decision to leave basketball, but I’m glad I did it.”

Kushen’s former club teammate and friend when he was young, Leo Francis of Santa Margarita, is another former basketball player who is thriving in track and field. He set a school record in the 200 last week, tied the school record in the 100 and won the long jump at the Orange County championships. He’s headed to Pennsylvania.

Temecula Valley High senior Jack Stadlman has a lot to smile about after running the 400 meters in 45.69 seconds.

(Mark Boster/For The Times)

Another former basketball player rising on the track is Jack Stadlman of Temecula Valley, who ran 400 meters in 45.69 seconds last month and also will be at Arcadia.

Kushen already had to overcome challenges with asthma and allergies during competitions. Then there was the most disappointing experience of his running career at the state cross-country championships last fall in Fresno. He lost by a little more than a second to Hueneme’s JR Lesher after leading in the final 50 meters.

“I believe I was the best runner in that field,” Kushen said. “I was happy he got that moment, but inside I was heartbroken.”

A goal that was two years in the making had come so close to being fulfilled.

“That was one of the toughest moments of my life,” the 17-year-old said. “I finally put myself in position to compete to get one of my biggest goals. I put it on my wall at the beginning of my sophomore year and to get outkicked in that last 50 meters . . . it really hurt. I threw up. It wasn’t from the race. It was from the realization I failed and lost.”

Kushen went back to work fixing what he learned from that race.

“I’m trying to develop that kick and speed,” he said. “You’re going to need that last final kick in the 1,600.”

Basketball’s loss is track’s gain. Kushen is looking forward to becoming one of the “Cameron Crazies” in Duke’s student section next year.

Could he be a ringer in Duke intramural basketball?

“I’m a little rusty,” he said.

Running has become his new passion, and he’s really good at it.