FOXBOROUGH, Mass. — Jerod Mayo turned down Bill Belichick’s offer to stay with the Patriots when he retired from football in February 2016. Three years later, the call came again.

So here Mayo stood Friday afternoon inside the team’s facility, weeks after he’d accepted Belichick’s invitation to join the coaching staff. Still barrel-chested and sweaty, as if he’d just trotted off the practice field, the former All-Pro linebacker told reporters why he’d become New England’s new inside linebackers coach.

“I always had the itch to get back into it, get back into coaching, get back into teaching,” Mayo said. “And any time you get an opportunity to learn from the greatest head coach of all time, you’ve got to kind of jump on that opportunity.”

Since Mayo removed himself as a key cog in the Foxborough football machine, much has changed in New England. The players, the coaches, the number of banners. But in the words of New England linebacker Kyle Van Noy, Mayo also “never really left.”

Neither did Dont’a Hightower, an up-and-coming linebacker in the final stages of Mayo’s playing career who now serves as the veteran heartbeat of the Patriots’ front seven — just as his position coach once did. Might the new dynamic between former teammates be strange?

“High, he’s like my brother. So I could sit here and lie to you and say, ‘Oh, we’re not friends anymore. It’s only a coach-player relationship.’ But he’s great,” Mayo said. “He’s working hard every day. It’s just good to have him out there.”

Mayo knows what he can expect from Hightower, who’s preparing to enter his seventh season in the league. As a first-year coach, though, he’s still learning about himself.

“I’m experimenting all the time. Does this work? Are the rookies really picking this up?” Mayo said. “So when the other guys come in, I’m able to do the same things.”

Even as a player whose coaching future was often prophesied during his playing days, Mayo admits there are parts of the job that have come as a surprise. The long hours, for starters. And then there’s the intake of information from Belichick — even though the team’s playbook has gone largely unchanged since 2015.

“Honestly, just the work that we put in in the classroom and then breaking down the message from Bill to the rest of the players. It’s difficult,” he said, “but at the same time it’s an exciting challenge.”

Certainly more exciting than the off-field life he turned to after retiring.

Mayo initially worked in financial services for the health company Optum. Later, he went into media at NBC Sports Boston, inching back closer to his football home. Each season, he broke down Patriots games and helped peel back the curtain on the most secretive and successful organization in football; his last step before slipping back behind it and into the life he’d missed so dearly.

Said Mayo: “You miss it, man. First of all, being stuck in Boston traffic every day stinks. It’s like you’re in the car two hours a day — you never want to do that. But other than that, it’s good. I’ve missed these guys, and I hope they missed me, so I’m happy to be back.”