By the time he was in fifth grade, Karl-Anthony Towns already stood 6-foot-3 and was getting noticed for how smoothly he moved on the basketball court.

Growing up as the son of a high school basketball coach in Piscataway, New Jersey, Towns took to the game early and spent long hours practicing with the help of his mother and father, who built a court for him in the family’s backyard. And though Towns showed so much promise that he was receiving Division I scholarship offers as early as his freshman year of high school, he faced his share of doubters—even among the people who you’d expect would support him.

WATCH: Video shows Karl-Anthony Towns was Mature Beyond his Years

“I had a coach when I was younger who said that two of my teammates were going to be the best players to ever come out of our program, and [be] the only ones to succeed,” Towns says. That seems improbable now, but Towns says the coach had his reasons. “I was playing off the bench—I never played.”

Rather than get mad, Towns used his coach’s criticism to get better. “You know, I just took that as motivation for me to prove him wrong,” he says.

The young Towns developed a routine that rivaled the preparation of any pro player: 1,000 shots made every day, six days a week. He spent hours studying tape of high-profile collegiate and pro players. And his hard work paid off, earning him a scholarship to Kentucky, where he played well enough to merit his selection as the first overall pick in the 2015 NBA Draft.

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Fast forward to today, when the 7-footer is working harder than ever to improve on his NBA Rookie of the Year performance last year. He and his Timberwolves teammates are taking aim at the playoffs. Whether they make it remains to be seen. But no one questions whether Towns can play.

“It’s awesome now to see that coach,” Towns says today. “When I get to talk to him about that, I think that [he knows] he was wrong.”

Follow other inspiring stories of pro and high school athletes proving their doubters wrong at #SayICant.