This story is part of Peak, The Athletic’s desk covering the mental side of sports. Sign up for Peak’s newsletter here.It’s the summer of 2011. Blake Drazner is about to go to eighth-grade football practice on a brutally hot Chicago day when he notices one of his classmates walking down the block with a backpack on and a basketball in his hands.He thinks to himself: Why is Jalen walking with a backpack in this heat? Maybe he’s going to a friend’s house.Then the same thing happens the next day: backpack, basketball, heat.And the day after that.And the day after that.And even on the days when it rains.It becomes a running joke in the Drazner family: Guess who I saw walking today?One day, Drazner asks Brunson what he’s doing and where he’s going, and Brunson tells him: Walking to the gym, working out, then walking home.Years later, Drazner looks up the distance: three miles there, three miles back, a workout sandwiched in between.“It’s a mentality,” Drazner says. “And he’s always had it.”It’s the summer of freshman year. Brunson is playing in Stevenson High School’s summer league, with three or four games in a day, usually lasting until 9 or 10 at night.After the final game, Brunson and his best friend, Connor Cashaw, pack their stuff and get in the car. They don’t have to say anything. It’s just understood what they’re going to do.Brunson tells Cashaw they have three buckets — academics, working out to get better and being social — but realistically he says they can only pick two. For Brunson, the choice doesn’t feel like much of a choice: academics and working out. It’s just part of him.Twenty minutes later, they’re in the gym at the Berto Center, the practice center for the Chicago Bulls. It’s one of the perks of having a dad on the coaching staff: You get to use the team’s facility.It’s clear in those late-night workouts that Brunson thinks differently than other kids his age: How can I get better? How can I take the next step? How can I prepare for when I’m on varsity? “That was the mindset,” Cashaw says. “One step at a time, one shot at a time.”It’s his senior year of high school. Brunson is a five-star recruit.Kansas, Villanova, Illinois — they all want him.His coach, Pat Ambrose, starts hearing about Brunson’s Friday nights after games. The rumors reach him via calls and texts.Did you hear Jalen was over there at 11 o’clock?I was at the gym the other night. Did you know Jalen was over there?So Ambrose talks to Brunson. He wants to make sure his star player isn’t worn out. How many teenagers can handle a midnight workout after a game?Brunson assures him he can. Ambrose can’t argue. Every day in practice, he sees the same energy, the same intensity, the same desire, the same mentality.