Between them, they have had multiple career-threatening surgeries. Both might have been finished. But both managed epic comebacks, returning to the top of their respective sports.

For Peyton Manning, the grind ended with his second Super Bowl win in 2016. For Tiger Woods, it continues with this week’s PGA Championship, following his stirring Masters victory last month. By rights, neither man should have expected a late-career resurgence, given their serious health concerns. Now, with Woods ascendant again, Manning reached out to him to share what he learned.

Watching Woods, Manning was reminded of their similarities, the obstacles both men faced to return to ordinary life, let alone the peak of athletic achievement, he told the Los Angeles Times.

“The one thing that really frustrated him was his limited practice repetitions,” Manning told the paper, describing his conversation with Woods. “He used to be a guy who was out there all day hitting balls. He used to try to get 1,000 contacts with the ball [in a practice session]. That could be putts, chips, whatever. He said: ‘Now that’s out the window. I can only do so many because if I do 1,000, I’m not going to be able to walk the next day.’

“I was the same way,” Manning said. “I was a guy that could throw all day. I was a stay-up-till-2-in-the-morning guy to watch film. I was a guy that was going to sacrifice my pre-practice stretch in order to be talking to the coach about the game plan during my stretch. Or staying in the meeting until 12:50 for a 1 o’clock practice, working on a new red-zone play.

“But once I had my injury, that all changed. I said: ‘No, I’ve got to go through my full rehab and pre-practice routine of warming my body up, my arm up. I’m going to sacrifice my last-minute film because the physical has to take over.’ I think Tiger kind of has the same thing.”

Manning, who retired shortly before his 40th birthday and is now 43, underwent at least four procedures on his neck and missed all of the 2011 season after having a discectomy and fusion. Woods, who turns 44 in December, has had four back surgeries. The upside is less pain and freer movement. The downside is what it takes to play again after those procedures. Woods, who had a 9:20 a.m. tee time for the final round of the Masters, had to get up at 3:45 a.m. to prepare his body for 18 holes of golf.

For both men, there also was a relearning, an acceptance of the new normal. Manning worked out at Duke University as he learned how to throw a football again. “I don’t believe I throw quite the same as before I was injured,” Manning told Sally Jenkins in 2013. “A lot of that is injury, a lot of it is being 37 years old, and a lot is playing with a new team. I’ve had a lot of change. It’s hard to know what percentage is what. I’m just trying to be the best player I can be in this new chapter.”

That transition was initially frustrating, another experience the two men shared, with Woods needing to adapt his middle-aged body to the demands of his sport.

“For him to see himself hitting shots that weren’t good, that can be a scarring thing to deal with,” Manning told the Times. “For Tiger, before his injuries, I guarantee you that the ball always went where he wanted it to go. And he was probably shocked when it didn’t. Now, all of a sudden, he’s hitting shots that are offline, not going anywhere, and chunking his chips. To see yourself doing that is like, oh, my gosh, it can make you just not want to play anymore or never be able to overcome that. I was kind of the same way. I was always really surprised when the ball didn’t go where I wanted it to go."

Winning the Masters last month took a toll on his body, Woods admitted afterward. “I’m pretty sore right now,” he said. “I’ve definitely let it all go today, and I ramped up the speed. I’m starting to have a little pop on the bat out there, which was good to see. I can promise you one thing: I’m not going to hit a golf ball [the Monday after winning.]”

He hasn’t played in a tournament since the Masters and is coming into the PGA Championship cold. The year’s second major begins Thursday at Bethpage Black on Long Island. Woods will be in a customary group of reigning major winners, along with Brooks Koepka and Francesco Molinari, teeing off at 8:24 a.m. His playing partners are significantly younger than Woods, as are most of the tournament’s top contenders. But Manning told the Times that he believes Woods isn’t done winning.

“I know from the injury standpoint how hard he worked, how determined he was, the adjustments he had to make,” Manning said. “I really think it’s just kind of the beginning. I don’t think that’s the last time he’s going to get crowned.”

Read more from The Post:

Thomas Boswell: Tiger Woods returned with a roar in a prodigal comeback for the ages

Barry Svrluga: Tiger Woods gives golf another unforgettable moment and begins a new chapter

‘Greatness like no other’: Serena Williams, Obama, Trump, Nike react to Tiger Woods’s Masters win