It’s 8:00 in the morning at Duke University’s Michael W. Krzyzewski Human Performance Lab. The campus outside is quiet, the sun is barely above the horizon. But inside this state-of-the-art training facility’s white walls, there’s music blaring and a six-foot-four, 23-year-old pitcher hard at work. It’s two days until Christmas and Aaron Sanchez has a flight to catch in four hours. But none of that matters now.

Sanchez has been in Durham, N.C., for nearly two months, working out 11 times a week with the same team of doctors who facilitated Marcus Stroman’s rehab from knee surgery. Presented with the choice of squeezing in one more workout or breaking for the holidays, sleeping in and catching his flight like a normal person, Sanchez opted to pack his bags the night before, train first thing in the morning and drive straight to the airport from the facility, sweaty clothes and all. The way he sees it, it wasn’t a choice. Sanchez wants to start 30 games or more for the Toronto Blue Jays this season, wants to fulfill the potential he’s shown in brief bursts since reaching the bigs, especially last June, when he was rounding into form as a starter just as he strained a lat muscle and missed six weeks.

“When I got hurt, I told myself, ‘All right, let’s just get through the year and then this off-season, you’ve got a lot of work to put in,’” he says. “That was my mentality. I was going to do the work no matter what I had going on.”

By his own admission, Sanchez was “weak” in 2015, which he feels played a primary role in the injury that interrupted his season. By the time he was healthy enough to pitch again, his spot in the rotation was gone. Instead, Sanchez was tasked with bolstering a floundering Blue Jays bullpen, a job he dutifully accepted and excelled at, but one that was decidedly his second choice. The lat injury, and the lack of core stability that likely caused it, derailed everything he’d been working towards since he was drafted by the Blue Jays at 17. He wasn’t going to let that happen again. (So far at least, it’s mission accomplished. Sanchez was named the Blue Jays’ fifth starter on Monday.)

Shortly before American Thanksgiving, Sanchez went to work. On top of the new training regimen, he consulted with a nutritionist, who put him on a strict diet that led him to gain 25 lb. over the winter, going from a lanky 190 to a toned 215. By the time he arrived in Dunedin, Fla., this spring and began throwing side sessions off a mound for the first time since he dominated in the playoffs, he was a completely different athlete.

“It’s a total transformation,” Sanchez says. “It definitely wasn’t easy. But I haven’t made a better decision in my short career.”

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Sanchez’s major-league career has indeed been short—he has just 11 starts and 54 relief appearances to his name coming into this season—but the road to get there was long. When the Blue Jays drafted Sanchez out of Barstow High School in California, they got a raw, unrefined product with an upper 90s fastball and big-time movement on his curve. They piggybacked him with other starters early in his professional career to preserve his arm, and had him make a bevy of mechanical adjustments as they slowly progressed him through every stop of their minor-league system. It was anything but easy.

“I struggled so much from the time I got into the organization with my delivery and making mechanical changes and all that stuff,” Sanchez says. “But I feel like I’ve done everything the right way from the moment I got here.”

He finally arrived as a polished product and member of the Blue Jays rotation to start the 2015 season, but then the lat injury exposed the missing key to his development: conditioning.

“I wasn’t able to do the things I needed to—I didn’t have the stability,” Sanchez says. “That’s been in the back of my mind all off-season. I just keep telling myself, ‘You’ve got to be durable. You’ve got to be able to get the job done.’”

As the clock strikes 10:30 a.m. inside the Krzyzewski lab, that job is nearly done. Sanchez hangs off a pair of TRX suspension cables, grunting through one final set of core-stabilization exercises before the holidays. He finishes his final reps and stands up straight, lifting the front of his shirt up to his face to wipe off the sweat. He gives fist bumps to both his trainers, grabs his keys and his water, and jogs out of the room, making haste for his car with less than two hours to catch his plane. He’s cutting it close. But he won’t be upset if the flight is missed, because the opportunity wasn’t.