The 36-year-old is playing like he's 26, spinning his career cycle in reverse after seemingly declining. But will the four-time NBA champion reveal his secrets or remain "The Big Enigma"?

SAN ANTONIO — If the same rules applied in this brief Tim Duncan interview that were in place in 2007 when the San Antonio Spurs forward was so famously ejected from a game for the simple act of laughing, then this would be a technical foul.

"The Big Stoic," "The Big Recluse" or — if you care for the classics — "The Big Fundamental" has agreed to field two questions about his latest Father Time-defying feats. And the first query about how he's doing it — "What drives you at this point in your career?" — inspired a smirk that, much like the secrets to his remarkable season, will go unexplained. And the answer, as is almost always the case when it comes to him, isn't nearly as compelling as his one-of-a-kind career.

"It's a lot of different stuff, but honestly I just feel healthy right now." Duncan told USA TODAY Sports during what evolved into a five-question session. "I feel like I have my legs underneath me for the first time in a while. My knee pain is way down, and I just feel good on the floor."

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There's always a healthy dose of mystery when it comes to Duncan, whose understated ways are as legendary as his sustained success (that's 14 consecutive 50-plus win seasons, for those counting). Never mind that there's so much to talk about: His ageless Spurs, led by a 36-year-old with more than 1,300 games under his belt who has somehow managed to be the best big man in the game again, have retaken control of the Western Conference from the Oklahoma City Thunder for now are behind only the Miami Heat for the best record in the league.

His oldie-but-goodie season has been every bit as impressive as that of the Los Angeles Lakers' Kobe Bryant, but Duncan — unlike his fellow future Hall of Famer — isn't about to about to spend his days discussing his greatness. It's his stubborn legacy, this distance he keeps between himself and a viewing public that ought to appreciate him now before he's gone.

There's nothing boring about what Duncan is doing.

"I honestly didn't know what to expect about these years," Duncan said when asked if he ever felt like the end was near in recent years. "My game has changed, and my role is different on this team. It's kind of reverted a little bit over the last however many games, and I'm being called on a little more.At a time when it seemed he would be hobbling his way toward retirement, Duncan is anchoring the league's third-best defense, entering Sunday grabbing 10 rebounds a game and blocking shots at nearly twice the rate of last season (2.7 a game compared to 1.5) while nearing his career-high mark of 2.9 a game set more than a decade ago. His offensive renaissance (17.6 points) is just as astounding, the uptick coming two seasons after his production fell to a career-low 13.4. In the eight games leading up to Sunday's showdown against Miami, Duncan had — in part because of Tony Parker's injury-induced absence for four games — averaged 23.6 points, 12.5 rebounds and 2.5 blocks.

"I feel good now. I just hope I can feel this healthy for another 10, 11, 12 games until we start the playoffs. If I can feel like this, and keep my knee feeling the way it does, I'll be excited about it."

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While Spurs coach Gregg Popovich has called Parker the best point guard in the game this season, he deemed Duncan the team's "psychological foundation." As Parker said Friday, "It's vintage Timmy." And everyone but the people he works with every day are the ones left wondering how he's doing it.

"He doesn't surprise me or amaze me every year," Popovich told USA TODAY Sports. "I think fans are (surprised), because listen — if you see him walk, that one leg doesn't even straighten out (because of knee injuries). Obviously he doesn't have the athleticism he used to have. But the guy is uniquely intelligent as far as knowing what his strengths and weaknesses are.

"He looks very cold-heartedly at himself. He looks at himself and says, 'This is my age, this is my body. What do I have to do?' "

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So how does he still do it? The question sparked similar responses from teammates and coaches alike, with most citing Duncan's steadfast regimen that includes a strict diet developed in recent years and off-the-floor training — from boxing to swimming, throwing tires, and running in the sand — that keeps him motivated and engaged. The result, nearly four years after his knee troubles led to 15 pounds of necessary weight loss that revived him, is a physique that has allowed him to be at his best again.

"He's really cut (physically)," Popovich said. "I look at him and tell him, 'You look like (Latrell) Sprewell, like Sprewell used to look. Just skin and bones, ligaments and tendons and things like that.'"

Spurs guard Danny Green said, "Everybody likes to think that maybe there's something behind the scenes that's special, something going on, but there's no real big secret. He takes care of his body. He does a great job with what he eats, his sleeping habits, stretching, working-out habits in the summertime…He stays in great shape."

Popovich, who won NBA titles with Duncan in 1999, 2003, 2005 and 2007 and deserves some credit for the way he has managed Duncan's minutes through the years, said his big man's desire to remain an elite player drives him more than anything.

"The minute he doesn't think he can perform like he is now, he'll just quit," he said. "He'll just walk in one day and say, 'Pop, I'm not doing this anymore.' He doesn't want to disappoint, doesn't' want to be a drag, doesn't want to be a hanger-on. And because of that, I think it motivates him to do what you see him doing this year…It's been a special time. His focus is pretty unique, and something that we really respect."

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The question going forward, of course, is whether the Spurs can stay healthy enough to make a title run. After downing LeBron James' Cleveland Cavaliers in the 2007 Finals, they have fallen twice in the Western Conference finals, twice in the first round and once in the second round. They had a 20-game winning streak and tied the Chicago Bulls for the best regular season record last season, only to fall to the Thunder in six games in the West finals despite having a 2-0 series lead.

"I wouldn't call it a disappointment in the last couple of years; there's only one team that's not disappointed," Duncan said. "Health considered, we're right there. We're right in the mix. We're pushing hard. Nobody expected us to be where we are, and everybody expected OKC and these other guys to be taking over the reign of this league. We're staying in the mix and we're excited about it."