Gregg Popovich had a great explanation for not following through with a widely held belief about his coaching career

Gregg Popovich was openly upset when Tim Duncan retired from the NBA last week.

Popovich, after all, had coached Duncan for 19 years, won five championships with him, and generally attributed the Spurs' long-run of success to him.

However, what has become apparent is that Popovich is not walking out the door with Duncan - despite what he's long said.

For instance, last year, after the Spurs signed LaMarcus Aldridge, Popovich said he had to give up the idea he would retire with Duncan when Aldridge wanted assurances that Popovich would still be coaching there for years to come.

On Wednesday, speaking from the US Men's Olympic Basketball Team practice, Popovich explained to ESPN's Ramona Shelbourne why he had to renege on his plan to leave with Duncan in typical Popovich fashion.

"You know what happened? I just got roped in. I had to keep making promises. Manu [Ginobili] was going to sign a few years back and he was like, 'Are you going to be here?' Tony [Parker], then Kawhi [Leonard]. Then when we were recruiting LaMarcus [Aldridge], he was like, 'Are you going to be here?' it just goes on and on. So I guess I can never stop, I can never retire.

"There's gotta be some time when we're trying to sign a free agent and he goes, 'Pop, are you going to be here?' and I say, 'Nope, I'm leaving next week.'"

Popovich was serious, however, when reflecting on Duncan's absence, telling Shelbourne of this upcoming season, his first full year without Duncan, "I think about the culture and his humor. I've been used to that for 20 years and now it's gone. I have to find that in some other way, some other power, some other player. I have to do something."

He added, "But life goes on for all of us."

While the Spurs will surely miss Duncan, at least they get to keep Popovich around for awhile longer - something that benefits the entire NBA world.