HOUSTON -- WEARING BLACK Crocs accented with two Fast U buttons, Pittsburgh Steelers running back Najee Harris shuffles through the doors of O Athletik just after 9 a.m. Muhammad Ali's likeness stretches across the back of his black T-shirt. A black Nike boxing backpack is slung over a shoulder.
Inside the cavernous downtown Houston gym -- co-owned by NFL players Adrian Peterson and Trent Williams with trainer James Cooper -- Harris fist-bumps his way to the back, where a small group of NFL players, boxers and local athletes have gathered to stretch before the morning workout.
Once in the back corner, Harris takes a seat on the black rubberized floor and trades his Crocs for a pair of sunset-colored Nike Air Max 270s.
In a day with three distinct types of workouts, Harris' footwear changes are checkpoints. Over the next 12 hours, the 24-year-old runs through a gauntlet of workouts in mid-July as he prepares for his second NFL season.
"Najee's like, if we have to lift a truck up over our head, then that's what we're doing," said Cooper, who has worked with more than 700 professional athletes. "He's not eager to do it like he's going to hurt himself. He's eager to do it to learn it, to understand the movement and get better at it."
After leading all rookies in touches a year ago, Harris is primed for another big season, though his training camp has been truncated after an offensive lineman stepped on his left foot. Head coach Mike Tomlin said the Steelers need Harris to remain a dominant, lead running back, and while offensive coordinator Matt Canada said Harris' volume of carries probably won't increase, his effectiveness will be a bellwether for the offense.
To prepare, Harris spent the offseason doing an intense regimen of workouts to fine-tune his body. It also served to strengthen him mentally, bolstering his confidence to handle the challenges ahead, including filling the leadership void created by Ben Roethlisberger's retirement.
"I think he'd be prepared to take a significant step in terms of embracing leadership and responsibility, regardless of who else is in the huddle with him," Tomlin told ESPN. "That's just where he is, and what he's done and where he desires to go."
On this day, Harris defined that leadership by finishing his workout schedule as the sun set on an empty high school football stadium near Houston.
"If I'm the last one on the field," Harris explained, "I know something deep down, maybe it's subliminal, I'm working harder than everybody."
Air Max 270
AS TEMPERATURES CLIMB in tandem with the unforgiving Texas sun, Harris stands in his red, orange and yellow ombre Air Max sneakers at the bottom of a steep, turf-covered hill behind the gym.
Sharply rising at a 42-degree angle above the parking lot, the 25-yard incline is the first hurdle of the day. In waves, Harris and the group hop, sprint, backpedal and bear crawl up and down the urban mountain, sweat pouring after a few repetitions.
This is just the warm-up.
Harris has been a fixture at these sessions since connecting with Peterson in 2021 as Harris prepared for the draft. After Harris finished his career at Alabama, Peterson invited him to Cooper's referral-only training sessions at O Athletik.
Cooper remembers standing beside Peterson and watching Harris cool down after one of his first workouts last year. With a chaw of tobacco in his mouth, Peterson spit into his cup and shook his head.
"He's going to be nice," Peterson said to Cooper. "He goes hard. He's going to be one of those guys who looks like you've got to protect him from himself a little bit."
During the 2021 season, Harris played more snaps than any other running back -- averaging 54.6 per game, per Next Gen Stats. The closest was Colts second-year back -- and NFL rushing leader -- Jonathan Taylor at 42.9 snaps per game. Harris also led all running backs in playing 84% of offensive snaps. Taylor, second again, checked in at 69%.
Even as one of the league's best three-down backs, Peterson, the Minnesota Vikings' all-time leading rusher, never played more than 76% of offensive snaps in a season.
"He's a big-bodied kid," Peterson said. "I caught myself a couple times looking at him. I'm like, golly, this boy's thick. He's not fat at all. He's just big-boned. He's thick and strong, and those big quads. Those big legs and upper body. He's well-put together. He's like the perfect dimension for a running back."
The 6-foot-1 Harris is training like he's never going to come off the field. Part of that preparation is further sculpting his physique into a hybrid force of power and durability. And, yes, that means putting on a little extra weight.
Listed at 232 pounds a year ago, Harris is adamant he played closer to 242. At mandatory minicamp, Harris announced he weighed 244.
"You need a certain amount of fat and a certain amount of weight depending on your running style," Cooper said. "Najee is having to find that. He's in great shape, because if you only go up a few pounds and you look like He-Man, but you're still moving like a Ferrari, that's great. That's part of the math."
WHEN HARRIS RETURNS to O Athletik after a quick lunch of turkey lettuce wraps and a grilled chicken kale salad, he slips off the black Crocs again.
This time, he replaces them with a pair of red and white HyperKO boxing shoes.
Harris first approached Cooper and Marshall Kauffman, a trainer at O Athletik and a boxing promoter, about boxing a year ago. He showed up at O Athletik on his first day off from group training to ask for more. While most in Cooper's workout group were resting and recovering, Harris wanted to keep going.
"I said, 'OK, you haven't had enough,'" Cooper said. "All right, this is good, this is interesting. I said, 'OK, let's box.'"
This afternoon, Harris is the lone member of the morning workout group still at O Athletik, but that's not out of the ordinary. He ties his shoes and rests on a bench in front of the ring while Kauffman tapes Harris' wrists and tugs a pair of blue and red boxing gloves over his hands.
First, they go through a maze of heavy bags and work on endurance, Harris running through different periods of nonstop boxing. Then it's over to the speed bag, and finally into the ring where he hits the mitts.
Marlen Esparza, a world champion flyweight boxer, is also training with Cooper in preparation for her upcoming fight.
In Esparza, Harris found a friend and boxing mentor. Early on in his Houston training, he started warming up with Esparza on the treadmill, running longer distances to match her output.
"He's strong," Esparza said, analyzing Harris' boxing technique. "He has good balance. He knows distance. He's quick, but he can calm down. He has his heart rate correct. ... He reminds me of great people where if you say you wanna do something, you'll do it."
The crossover between football and boxing isn't new. Other players, such as Peterson and Williams, have incorporated it into their offseason training for years, finding value in boxing's hand-eye coordination and techniques that can translate onto the field, like a stiff-arm.
For Harris, boxing satiates his competitive nature in the offseason and is another tool to prepare him for a large workload.
"In boxing, they train to go the distance, to go 15 rounds," Harris said. "In football, I always want to train myself to go all four quarters, because we played a lot of tight games last year. To go 15 rounds, that's something that we always say in football. Just beating the man in front of you, find ways. I fell in love with boxing."
Zoom Rival XC 5
BEFORE DRIVING 45 minutes for his final workout of the day, Harris stops at JuiceLand for a smoothie and watermelon juice -- a recent favorite of his for its hydration and reputation for speeding up recovery.
Never still for long, Harris jumps up after finishing his juice and heads home to grab his final pair of shoes for the day. He arrives at Fulshear High School just after 5 p.m. and starts out wearing his Air Max 270s for warm-ups directed by Will Collins, a track guru who runs Fast University, a running program that caters to elite athletes. Collins analyzes every aspect of running, from velocity to form to foot strike to get-off techniques. Harris found him when he started asking around for the best track coach in Houston.
Working out with a group that includes an Olympic skeleton racing athlete, collegiate track stars, an NFL wide receiver and high school track prodigies, Harris slips on a vest and a pair of white Zoom Rival XC 5s. Spikes emerge from the hot pink soles, gripping the track as he runs a series of 100-meter sprints while Collins and his assistant monitor an array of stats that are transmitted onto a laptop from the vest.
In between sprints, Harris sits on the turf as the day catches up to him, eventually lying prone, his head resting on his hands. He talks about the need to work out, but it's not just to get physically stronger.
"I need to feel confident in myself," Harris said. "I need to feel like I'm ready to endure a load if it's placed upon me for the Steelers, like I did last year.
"I always want to do better, I want to do more," he continued. "I don't want to take anything lightly or for granted."
"I need to feel confident in myself. I need to feel like I'm ready to endure a load if it's placed upon me for the Steelers, like I did last year."Najee Harris
As the sun slips behind the high school, Harris walks to his car to head back to his apartment in Houston. He'll get home between 10 and 10:30, sometimes later if he stays to analyze his running data with Collins or stops for a steam room session.
"People might say I might do too much," Harris said. "But I want to feel comfortable when I step on the field.
"And if I feel like I didn't do as much or if I feel like I cheated the game or something, then I'll get mentally defeated in a way."
Harris' coaches aren't worried about the running back's workload because they trust him to know his limits.
"That's who he is, and that's what got him here," running backs coach Eddie Faulkner said. "During the season, it's never been an issue where he's doing too much and it's keeping him from being who he needs to be for us."
The next day is Wednesday, typically an off day, but not this week.
In less than 12 hours, Harris will shuffle through the door of O Athletik, Crocs on his feet and the next change of shoes in his bag.