As the Spurs beat the two-time defending champion Miami Heat in the NBA Finals earlier this month, Duncan was asked several times about his future, as he has been for the last five or six years. He was noncommittal, saying he would take some time after the season ended to mull his decision.
But after Game 5, most of the Spurs said they expected the group to return and now Duncan has reached his decision, which was first reported by Yahoo! Sports. He will make about $10.3 million next season in the final year of a two-year agreement that was drawn up specifically to allow the Spurs the financial flexibility to surround Duncan with top-shelf talent.
"He feels a responsibility to his teammates," Spurs coach Gregg Popovich said after the team won the championship. "He enjoys them. He wants to hang around as long as he can while he's useful and while he's having an impact on the game. He takes care of his body. He works out all summer long with a variety of different things, boxing, swimming. He's very careful about what he puts in his body, so he does everything he can to maintain a level of play.
"At some point," Popovich added, "that will stop."
But not this year.
When Duncan looked around at the Spurs, he saw every reason to come back and try to do just about the only thing the Spurs haven't done during his 17 years there — win back-to-back titles.
In Popovich he has perhaps the best coach in the game, one who has established a culture of teamwork, success and stability that is unparalleled in the league. In Tony Parker and Manu Ginobili, he has two trusted teammates who have been by his side for years, have sacrificed money, fame and statistics right along with him to build the Spurs organization into the envy of the NBA.
And in Finals MVP Kawhi Leonard, Duncan has a young, fresh-faced star on the rise to carry more of the load as the Big Three get older.
"With the front office putting the teams together that we've had and us playing smaller roles and our roles changing over the years, and us happy to accept the roles that we're in, I feel we can do it until we feel we don't want to do it anymore," Duncan said two weeks ago.
Perhaps as important as anything, Duncan is still one of the best big men in the league. He was named first team All-NBA in 2012-13 as he helped the Spurs to the finals, where they lost to the Heat in a heart-breaking seven-game series.
This season, Duncan averaged 15.1 points, 9.7 rebounds and 1.9 blocks in just 29.2 minutes per game, playing in a system expertly devised by Popovich to limit the wear and tear on his body. He shot almost 57 percent in the finals and dismantled Heat star Chris Bosh, who grew up with a Duncan poster on his bedroom wall.
"We've been on our last run for the last five or six years from how everyone wants to put it," Duncan said. "We show up every year, and we try to put together the best teams and the best runs possible because what people say doesn't matter to us.
"As I said, as long as we feel we're being effective, we're going to stay out here and we're going to play. We feel like we can be effective, and we have been."