On a glorious evening recently, the runner Markelle Taylor — otherwise known as “Markelle the Gazelle”— entered the dark sally port and crenelated towers of a place he was once overjoyed to leave behind: San Quentin State Prison. Accompanied by volunteer coaches from the prison’s 1000 Mile Club, Taylor, who was incarcerated for 18 years for second-degree murder, couldn’t wait to see his brothers, lifers all.

Taylor, 50, fully earned his long standing nickname in 2019 at the San Quentin Marathon, where he barreled through 104 and a half laps around the prison yard with its gantlet of 90-degree turns, fast enough to qualify for the Boston Marathon, which he ran six weeks after his release.

After he finished his sentence, Taylor sought to return as a mentor to his running buddies still inside. Three months ago, he finally got the thumbs up from state corrections officials. Now he returns to San Quentin to coach runners every other Monday.

On this visit, it took less than a minute for him to bump into an old friend in blue prison garb. “Hey!” said Sergio Alvarez, who has been incarcerated for 10 and a half years. “I see you in the paper, man, and on TV. You’re doing what’s right and speaking out, bro.”

It means a lot to Taylor to be mentoring with people who mentored him, especially Frank Ruona, who turns 78 next month and plans to retire after 18 years as the club’s head coach.

“He’s a prime example of the qualities that make a good coach,” Taylor said. “Faithful, loyal, honest, no judgment, an accomplished fast runner with records and time under his belt.”

But Taylor brings his own special qualities to his new role. “Being a lifer, or an ex-convicted person who did hard time, I bring that flavor of connection,” he said. “I want to give them hope, just be there for the guys any way I can. To help them get out and be better athletes.”

The runners filtered in across the yard’s scraggly grass, dodging a baseball game in progress, a Spanish language choral rehearsal and a smattering of Canada geese who are the prison’s feathered lifers. Track workouts begin at 6 p.m. after dinner and the mandatory daily head count.

Tim Fitzpatrick, who is stepping in as Ruona retires, called the runners together, their evening silhouettes casting long shadows on the track’s crumbly dirt. Fitzpatrick, the finisher of 28 marathons and 38 ultra marathons, is assuming Ruona’s mantel along with his wife Diana, the president of the 100-mile Western States Endurance Run and a two-time Dipsea champion, and Jim Maloney, another longtime coach and a restorative justice facilitator at the prison.

“We want a training run, not a straining run!” Fitzpatrick said of the night’s workout — six pickups, or fast paced intervals, each prompted by an exuberant loon-like whistle he concocts with his hands.

At “Ready … set … exercise!” Taylor started pacing his fellow runners around the track, the trickiest stretch being a right angle that funnels into a gap between chain link fences. During breaks he chatted with old friends like Darren Settlemyer, a fellow Jehovah’s Witness who first suggested that Taylor join the running club, knowing that he was stressed out by a close friend’s suicide and an upcoming parole hearing. When Taylor started running, “everything connected mentally and spiritually,” he said. “I was free four years before I was released.”

Taylor grew up a victim of domestic and sexual violence and was addicted to alcohol. He was 27 years old when he was sentenced to 15 years to life for assaulting his pregnant girlfriend, which led to the premature birth and eventual death of their child.

“I didn’t know how to process all that misplaced anger,” he said. “When you feel you ain’t nothing, you tend to gravitate to the negative. I feel a lot better about who I am today. I’m pretty conscious of trying to hold on to the goodness in my life.”

There’s a bounty of goodness. Taylor’s return to San Quentin is part of an extraordinary year in his life. He’s one of the subjects of “26.2 to Life: Inside The San Quentin Prison Marathon,” a documentary film by Christine Yoo. He has been zipping around the country to film festivals, walking red carpets from Santa Barbara to Woods Hole and routinely receiving standing ovations during post-screening Q. and A.’s. His naturalness and warmth as a speaker have allowed him to connect with audiences about his story and the need for prison reform.

“Markelle gives us hope, which is a blessing,” said Kirivuthy Soy, a member of the 1000 Mile Club. “Him getting out shows that just because you’re a lifer doesn’t mean you’re going to be in here forever.”

For Taylor, the enthusiastic embrace by audiences and the experience of seeing the film repeatedly is gratifying and healing. “The more I watch it, the more it helps me to process internally what I’ve been through in my lifetime and continuing to be accountable to the pain and suffering I’ve caused,” he said. “The speaking engagements give me a sense of purpose and well-being and helps with my sobriety and being clean.”

Twenty-two years sober, he continues to attend Alcoholics Anonymous and Narcotics Anonymous meetings in Marin County, where he lives. “I think if you don’t go it’s like forgetting where you came from and you can stumble that way,” he said.

His life as a film festival darling feels far removed from his day-to-day reality. Like many formerly incarcerated people, he struggles to find meaningful and well-paying employment: Taylor earns $17.25 an hour as a supermarket cashier. “I get along with everybody and I’m fair,” he said. “But being Black I have to work harder than anybody else, and with a criminal background it’s really tough. They will judge you and might not even be conscious they’re doing it.”

His willingness to ask for help is a strength. He is also not afraid to go after what he wants. At a screening at San Quentin on Jan. 6, he stood up at an open forum and asked the warden, Ron Broomfield, if he would allow him to come back in as a volunteer. “He kind of put me on the spot,” Broomfield recalled. “He didn’t realize that I’m a big advocate of returning citizens coming back in to mentor, because they can reach people in ways that we can’t.”

Broomfield, now the director of adult prisons statewide, is also a co-chair of a committee set up by Gov. Gavin Newsom of California charged with transforming the prison into the San Quentin Rehabilitation Center, a concept modeled on campuslike Scandinavian prisons. The initial plans call for revamping a furniture factory where Taylor stained and finished chairs for 50 or 60 cents an hour into a $380 million education center, with more space for restorative justice and other programs.

The documentary has led to droves of runners asking to be volunteer coaches; at the evening workout, there were 15 runners and 14 coaches, a teacher-student ratio most schools would envy. Among the newbies was Peter Goldmacher, vice president of investor relations at Dolby Laboratories, who saw the film about a year ago “and thought I definitely want to get in on that,” he said.

Taylor is rebounding from a torn meniscus and other injuries. He took some time off and felt lonely when he didn’t run. Between traveling and his job, he hasn’t been able to train as consistently as he’d like. “When I’m running, I’m much more focused,” he said. “It helps lift me up.”

This fall he plans to run the Chicago Marathon and the New York Marathon. After running three marathons in a row in under three hours, most notably a 2:52 in Boston two years ago, he would like to hit the mark again. But his mission right now is “to be an ambassador for lifers,” he said. “What’s important is to run with joy and love and a sense of purpose and not chasing my own personal goals.”

With newfound confidence, he’s batting around possibilities — maybe a TED Talk or expanding his Markelle the Gazelle athletic gear line.

“I can’t change the minds of the masses,” he said. “All I can do is to live the best possible self I can. Doing that can radiate like a light — so that everyone else can see.”