It was 15 years ago this spring that Michigan Tech decided to end its football program, in a move that Joe Berger figured would end his playing career.

His unlikely story — from a program that opted to drop football before reversing course, to nearly a decade spent mostly as a NFL journeyman and ultimately to a starting job with the Vikings — could have continued for one more season.

Berger had offers from the Vikings and Detroit Lions for 2018. He had played all but two snaps for Minnesota in 2017, emerging healthy from one of his best NFL seasons, and could have picked between a season in the new Vikings practice facility, with longtime teammates and trusted coach Tony Sparano, or a season in his home state with the offensive line coach (Jeff Davidson) that Berger said had made football fun for him again.

Perhaps the improbability of his career arc had informed Berger’s pragmatic sensibility about it all, or perhaps his strong post-football prospects — he holds an engineering degree from Michigan Tech — made the vision of life after the NFL easier to grasp.

In the end, when both the Vikings and Lions offered him contracts at the start of the league year on March 14, Berger turned them down. And on Friday, after giving himself just a little more time to make sure he was at peace with his decision, Berger decided to call it quits.

He announced his retirement Friday, ending his career after 13 seasons in the NFL and a seven-year run with the Vikings that culminated in Berger starting 49 regular-season and playoff games over the past three years at three different positions.

“A decision like this, there’s a million things that go into it,” said Berger, 35. “I had my mind made up when I left in January [after the Vikings’ NFC Championship Game loss], but there’s no way to guarantee that. In the offseason, my intention was to sit on it, think about it, see what free agency had. The last week was not to sway my decision, but to confirm my decision.”

Turning down the Vikings’ and Lions’ offers, Berger realized, essentially made his decision all but final. Playing in his home state and reuniting with Davidson — his position coach from 2011-15 in Minnesota — was intriguing, Berger said, but his heart was still with the Vikings. If he was going to play, he said, it probably would have been with them. “It would have been hard to leave Minnesota,” he said. “I don’t know if they would have gotten me to Detroit.”

If he wasn’t fully committed to the idea of playing, though, he said wasn’t expecting the Vikings to wait around for him, and he didn’t want to keep them on a string.

“Once you [turn them down], the contract’s not going to get better,” he said. “You kind of know once you turn a team down, that’s it. Maybe it wouldn’t be for some of the big-time guys, but for me, it wouldn’t be done right [to make them wait].”

With Berger planning to move on, the Vikings added Rosemount native Tom Compton to their offensive line on Thursday. Guard Jeremiah Sirles also signed a one-year deal with the Carolina Panthers.

Berger, meanwhile, will take the summer to enjoy the house he built in his hometown of Newaygo, Mich., with his wife, Abby, and their four children, before figuring out what’s next. He said he’s already had discussions about “buying a little manufacturing shop,” or going to work as an engineer. “That might end up being what I want,” he said.

He doesn’t, however, plan to spend the spring calling his agent, Tom Tafelski, and asking him to find him a team. Friday, Berger sounded content with the choice he had made.

“I’m not trying to pretend I’m not going to miss it,” he said. “Nothing can replace being with the guys. But I had to ask myself, ‘Could I be happy for those guys when they’re at training camp having fun together, or when they make the playoffs, or when they make a run? Yeah, I think I can.’ I made the decision based on what I feel, and that’s what I’m doing.”