He is seated right in front of you, his electric smile, gymnastic wit and spirited candor often tumbling into a generous laugh. Warren Sapp is clearly and enthusiastically here.

But the mood is different when the conversation turns to his August visit to the NFL Hall of Fame in Canton, Ohio, for the 2022 induction ceremonies, an annual tradition that reunites dozens of pro-football legends voted into the hall over the decades.

A game-changing defensive lineman whose agility redefined what men his size could do, Sapp was inducted in 2013, but his Canton visits remind him not so much of past glory but of his unpredictable future.

“Every year I go back, there’s a couple (Hall of Famers) that aren’t there. And there’s a couple that ARE there, that AREN’T there. You understand what I’m saying?” he says.

A Miami Hurricanes legend now living in Hollywood, Sapp believes the cost for his years in the football trenches is about to come due: He is convinced he has CTE, the progressive brain disease linked to repetitive head injuries.

Sapp faces this reality in a new documentary film, “Life With CTE,” scheduled to screen at the Fort Lauderdale International Film Festival on Nov. 5.

“When you can’t remember something that’s almost like writing your name … it’s a very scary and helpless feeling,” says Sapp, 49, in a scene filmed at Raymond James Stadium, where his name is part of the Tampa Bay Buccaneers’ Ring of Honor.

Currently, CTE can only be diagnosed after death through brain tissue analysis, with football players, hockey players and injured military the primary focus of most studies. Once it takes hold in the brain, the disease continues to spread even after head injuries cease.

A 13-year veteran of the NFL with the Tampa Bay Buccaneers and Oakland Raiders, Sapp agreed in 2017 to donate his brain to the Concussion Legacy Foundation at Boston University’s Chronic Traumatic Encephalopathy Center, writing in The Players’ Tribune that he wanted to “make our game safer for future generations.”

“I’ve always said I want to leave the game in better shape than when I got into it,” he says. “This became interesting to me because it was something that was going to be a lasting effect. Not only could I leave my bust in Canton, I’m going to leave my brain in Boston.”

He cited similar motivations in a recent interview for agreeing to make the short film “Life With CTE,” directed by Mike Mentor, a former college football player-turned-filmmaker.

In the film, Dr. Ann McKee, director of Boston University’s CTE Center, reports that by the time Sapp registered to donate his brain to the program, its researchers had studied 111 brains of NFL players. CTE was found in 110 of those brains.

The U.S. National Institutes of Health, the world’s largest biomedical research agency, recently rewrote its official guidance to formally acknowledge, for the first time, a predictive link between repeated traumatic brain injuries and CTE.

The change came after new research by Harvard University, Oxford Brookes University and 11 other academic institutions, alongside analysis from the Concussion Legacy Foundation, found a “causal relationship” between repetitive head injuries and CTE. The report urged “immediate action” to stop development of the disease, especially among children.

Sapp says his target audience for “Life With CTE” is parents who allow head injuries to begin at a young age. He hopes the film will encourage them to divert their children into less dangerous pursuits, including books and chess, swimming and baseball, at least until they reach high school.

“I want it to educate and open the eyes of parents out there,” Sapp says. “You don’t need to put your kids through this banging. You really don’t. Please save them.”

‘I go blank on you’

He recently sat for a conversation about “Life With CTE” in downtown Fort Lauderdale, and for anyone who has seen his media work — from football talk to “Dancing With the Stars” — it was pure Sapp: Confident, thoughtful analysis, delivered efficiently, with a sprinkling of humor.

But the interview took place a day later than originally scheduled because Sapp forgot about it. Traveling back from a vacation in Hawaii, he had a layover in Los Angeles, where an old college roommate suggested they attend the Denver Broncos-Los Angeles Chargers “Monday Night Football” game. Sapp agreed and pushed back his connecting flight to Fort Lauderdale.

“I go blank on you,” he says of the interview that was set for the following day. “In the middle of the game, something says, ‘You were supposed to be somewhere tomorrow.’ I looked at the calendar … and I said, ‘Son of a …’ ”

Sapp says he first became concerned about his brain function a couple of years ago, during a drive to see a friend of 25 years at his office in Miami. Somewhere on Biscayne Boulevard, he forgot where he was going.

Glancing at his phone, the date reminded him of his destination — but he couldn’t remember where his friend’s office was. He pulled over, called another friend and explained that he couldn’t remember how to get there. His friend laughed.

“I hang up the phone, and a rush just comes over me. I’m pissed. I swing the car around, go back home, and just sit there for the rest of the day,” he says. “I’m almost sitting there in tears.”

Sapp has tools that help him get through his day-to-day responsibilities, including a notebook where he writes down “everything.” He has memory games on his phone that he plays each day.

“Every morning, I’ve got to go to that schedule, I’ve got to go to those notes. If I don’t, my whole day will be thrown off,” he says.

‘I’d never seen him cry’

The filmmaker, Mentor, approached Sapp about making a documentary after noticing his friend struggling to remember things.

Before studying film, Mentor was a defensive lineman at Wagner College in New York. A teammate introduced him to Sapp in 2018, and while Mentor was in graduate school, the two began working on Sapp’s podcasts.

“There were times that I would tell him things and he would really just blank, and he wouldn’t remember. And I was, like, ‘Man, I know he’s not being an a–hole. He really doesn’t remember. He has no recollection,’” says Mentor, who had two serious concussions of his own early in his college career.

Mentor, 30, was speaking during a break from work at Warner Bros. Studios in Los Angeles. His most recent work came as a production assistant on “Amsterdam,” directed by David O. Russell, and Damien Chazelle’s upcoming release “Babylon,” starring Brad Pitt.

After the pandemic delayed the project for a couple of years, filming on “Life With CTE” took place this year, in a matter of weeks, from late March to early April in Hollywood, Tampa and Sapp’s hometown of Plymouth, near Apopka, Fla. (His childhood home sits on Warren Sapp Drive.)

“He’s so open and willing. We’ve been talking about CTE all the time over the past couple of years,” Mentor says.

One scene takes place in Sapp’s mother’s house in Plymouth, where she has created a shrine in a room filled with trophies, jerseys, magazine covers and other mementoes of his career. It’s a place heavy with memories and, stroking a large trophy he had given to his grandmother, Sapp weeps.

Speaking of that scene, Sapp says: “It just brought back 25 years of grandma and mom. My grandma told me when her and my mom dropped me off at the Florida-Georgia [high school] all-star game, ‘No matter where you go on this Earth, don’t you forget where you come from.’”

Mentor has another interpretation.

“I could feel that day was very emotional for him. Walking in that room and seeing all of his accomplishments, and knowing there was a price to pay for those accomplishments, and now we’re here talking about it on camera,” Mentor recalls. “I’d never seen him cry before. I never thought I would. He was very honest, and I think it showed on the screen.”

Tony Dorsett to Tua

Sapp has seen the distressing road map of CTE in the lives of other players, including fellow Hall of Famer Tony Dorsett, whose steady decline he’s witnessed at annual induction ceremonies in Canton.

“Brother, we’re talking about one of the sweetest running backs we all knew back in the day. (He’d) juke you down, with a star on his helmet, hole in the roof, so God could watch,” Sapp says of Dorsett’s Cowboys Stadium heyday. “Now I walk in the room, and it’s like a shell.”

It’s an image Sapp can’t shake.

“What makes me so special that that’s not my path?” he says, his voice softening. “(That) when I walk in the room and look at my babies and won’t be able to recognize them? Or have an issue recognizing them? Or have an issue having a conversation with them? What makes me so special that that’s not my fate, too?”

CTE has been connected to suicides of several NFL players, including former Miami Dolphins linebacker Junior Seau, and to the shocking case of Aaron Hernandez, a former New England Patriots tight end who died by suicide after being convicted of a 2013 murder.

Sapp says he doesn’t feel any of the mood swings or aggression associated with CTE. He has been charged with assault several times since his retirement after the 2007 season, including one incident in 2015 that got him fired from the NFL Network.

Seau’s death hit home for Sapp, who was with him on Showtime’s “Inside the NFL” just days before he fatally shot himself in 2012 at age 43. Studies by the National Institutes of Health concluded Seau had CTE.

“He came in there and he was the same gregarious, lovable buddy that we all knew. Just Seau. And then a week later, he shot himself. … It’s just more than sad,” says Sapp, who remains critical of the NFL’s response. “The silence behind it. That’s the thing, the silence behind it. Like, ‘Oh, football didn’t have anything to do with this.’ What?!”

Sapp says he also was disturbed by the Miami Dolphins’ response to quarterback Tua Tagovailoa’s injuries in successive weeks, the first described as a back issue and the second a head injury four days later that saw him carted off the field on Sept. 29 during “Thursday Night Football.”

The Dolphins were criticized for allowing Tagovailoa to play so soon after the first injury, which caused the quarterback to stagger noticeably.

“I never saw that man grab his back or his neck. You know what I’m saying? But I did see his head hit the ground, and then he wobbled,” Sapp says. “C’mon, man. They want to tell us we ain’t watching what we’re watching.”

Dolphins coach Mike McDaniel told Sun Sentinel reporters that Tagovailoa’s first injury did not involve his head, which justified the decision to play the quarterback. McDaniel said he is vigilant when it comes to monitoring concussion issues.

“I do not have any, like absolutely zero patience for — or will ever — [putting] a player in a position for them to be in harm’s way,” McDaniel said.

More than three weeks after his Sept. 29 head injury, most of that spent in the NFL concussion protocol, Tagovailoa played on Sunday without incident in a Dolphins win over the Pittsburgh Steelers.

A few days before that game, Dr. Chris Nowinski, a neuroscientist and CEO of Boston University’s CTE Center, issued a statement on the “horrific Tua incident.”

“No amount of money can make up for brain damage,” said Nowinski, a former Harvard University football player.

Sapp says oversight is even more important when it comes to kids. He believes youth tackle football should be eliminated before high school to reduce the cumulative total of hits a player takes in his career.

“You know down here in South Florida, Saturday afternoon at 1 o’clock, my God. … The littlest little monsters you can find and they’re out here stomping and hitting,” he says. “And I’m like, no, no, no. We know better now. Why aren’t we doing better?”

Sapp says his son, Warren Sapp II, a linebacker at Florida Atlantic University, only began playing football in high school after friends pushed him into it because of his famous father. Sapp II’s passion and future is in technology, his father says, proudly.

For his part, Mentor also has some personal motivation.

“I have friends now who have kids who are going to start playing tackle football, and just seeing the effects on Warren, I felt like if I can create this story and get it out there … I’m just literally trying to save kids, guys in college and grown men,” Mentor says.

“Life With CTE,” which clocks in at under 15 minutes, will have its FLIFF screening at 3 p.m. Saturday, Nov. 5, at Savor Cinema in downtown Fort Lauderdale, with Sapp and Mentor in attendance.

The two also are scheduled to walk the opening-night red carpet at Hollywood’s Seminole Hard Rock Hotel & Casino on Friday, Nov. 4, before FLIFF’s opening-night feature, a 7:30 p.m. screening of the Peter Dinklage-Shirley MacLaine comedy “American Dreamer.”

Sapp says the FLIFF screening will be the first time he’ll see “Life With CTE.” Mentor sent him a link to the film, but Sapp didn’t click it. He prefers to experience it with an audience.

“I want to watch it first in a theater. I’ll probably break down and cry myself,” he says, laughing.

“Life With CTE” screens at 3 p.m. Saturday, Nov. 5, at Savor Cinema, 503 SE Sixth St., Fort Lauderdale. Tickets cost $13 for general admission; and $10 for seniors, students and first responders $10. Visit FLIFF.com.