The Spurs enjoyed plenty of laughs last season while recording a franchise-record 67 wins, but the good times just weren’t good enough anymore for Tim Duncan

In revealing why he retired after a 19-season career in which he left an indelible mark on the NBA and pro sports in general, Duncan pointed Wednesday to a simple reason.

“I started not enjoying myself as much,” he said. “It wasn’t fun at times. Obviously when that point comes, where it’s not fun anymore, I’m done.”

Duncan’s comments, his first since he announced his retirement Monday via a straightforward press release issued by the Spurs, came in a wide-ranging, 75-minute interview with longtime friend and fellow Virgin Islands native Rashidi Clenance for the online radio station ViVid Streaming.

Although he said he could probably continue to play, Duncan, 40, said the time had come to stop.

“I really have no regrets,” he said.

Since making his announcement, Duncan said he has been “blown away” by all of the “incredible notes and messages” that have arrived from all corners of the basketball world.

“I didn’t expect all of this, didn’t expect the reaction I got,” he said. “It’s amazing. I’ve spent the last two days trying to respond to everybody to make sure they know I am thankful for their messages, their words.”

Perhaps the most humble superstar in NBA history, Duncan fittingly spent Monday at home watching the Discovery Channel rather than checking out the coverage on ESPN or NBA TV.

“It’s the way I’m built,” he said. “I didn’t want to sit there and watch it all day.”

But he said he did view two tributes, the most touching of which came Tuesday in the form of Gregg Popovich’s 15-minute session with the media. The only pro coach Duncan ever had choked up several times while talking about the “most real, consistent, true person I have ever met in my life.”

“I about lost it on that one,” Duncan said.

His girlfriend, Vanessa Macias, made sure he also watched a “great segment” authored by former Spurs teammate Bruce Bowen. But other than those two, Duncan skipped the career eulogies.

“Luckily, I’m not dying,” he said. “I’m just moving to the next chapter.”

And what will that next chapter hold?

“That’s the beauty of it, there is no script,” Duncan said. “It’s the first time in 20-something years, I don’t have a script. I don’t have somewhere I have to be and something I have to do. So I get to go out and enjoy my kids even more and do more of living. It will be great.”

Several general managers and coaches around the league have jokingly asked him if he would like to change his mind and play for someone other than the Spurs. One of those invitations came from a former teammate, Golden State coach Steve Kerr.

“I’ve gotten a lot of funny offers,” Duncan said. “That feels like love more than anything else.”

But with two aching knees, Duncan stressed there is no turning back.

“As of right now, sitting here, yeah, I’m pretty sure I’m going to stay retired,” he said.

Chatting with Clenance from his San Antonio home, Duncan reflected on his place in NBA history, saying he isn’t about to get caught up in where he rates among the game’s greats.

“I don’t really care how the ranking goes,” he said. “I’m in the conversation. I’m OK with that. That’s above and beyond anything I ever thought I would be. That in itself is an honor.”

The Spurs drafted Duncan No. 1 overall in 1997 after winning the NBA lottery, but he got off to a somewhat shaky start after graduating from Wake Forest.

“I walk into summer league and run into guys like Greg Ostertag and Jermaine O’Neal,” Duncan said. “These guys destroyed me, beat me up. It didn’t go well. It didn’t go well at all. I was sitting there shaking my head like, I don’t know.

“But then I went through the rest of the summer, worked out in Colorado with David (Robinson) and just started finding my way.”

It was a golden path that eventually led to five NBA titles, two league most valuable player awards and three Finals MVP awards.

“The good old days when the knees were really good,” Duncan said of his playoff prime.

With memories of his days growing up in the Virgin Islands never far from the conversation, Duncan said he was proud of how the Spurs built a dynasty with so many international players, including Big Three sidekicks Manu Ginobili of Argentina and Tony Parker of France.

“You look back, and it’s an amazing, amazing feat to have all these kids from all these different places come together and be what we were,” he said.

Another big topic was Duncan’s unselfishness. Through the years, his team-first approach cost him millions but allowed the Spurs to go out and get the players they needed to contend for titles year after year.

“I took a little less money at certain points,” Duncan said, “so we could stay competitive, so we could bring players in, so that we could put pieces around (me), so we could win championships. That’s all it was about.”

Duncan was asked if it ever bothered him that players who weren’t in his league sometimes made more money.

“The honest truth is, and people may or may not believe me, I didn’t really know from year to year what everybody was making,” Duncan said, “and I think that’s the best perspective to have.”

Shortly after the interview ended, a five-paragraph thank-you letter to fans and San Antonio from Duncan appeared on the Spurs’ website. In the farewell note, he said what he would remember most about his career are the people he met along the way.

“The fans inside the arena and out,” Duncan wrote, “the staff and coaches who pushed me and held me together, the teammates (and even opponents) who will be lifelong friends, sharing my ups and downs with family and close friends, and, most importantly snapshots of my kids growing up and reveling in watching Dad work. That is what I will cherish most.”

Although there weren’t any tear stains on the letter, he did choke up at the end of his interview.

“It’s been fun,” he said, pausing to collect himself after his voice cracked, “and the next chapter will be fun, too. I really enjoyed the ride, the cheers and the laughs, the highlights and the lowlights, and everything that comes with the package.”