He always played defense, and getting an honest answer out of him was like wrestling him for a rebound.

When Mourning retired from Basketball Thursday, it was striking to realize how much he has changed. He stood behind a lectern inside his second home at AmericanAirlines Arena, looked everyone in the eye and spoke eloquently about his passion for the game.

"With everyone's career, with everything you do, a clock starts," he said. "Father Time catches up with everybody."

Mourning, almost 39, decided to walk away without "a limp or a cane." He paused a couple times, admitted he was on the verge of tears. He also chuckled, made fun of himself, waxed philosophical, got opinionated, demurred to his wife. He is a fascinating middle-age man.

During his years with the Miami Heat , we watched Mourning block shots, flex biceps, foul out, brawl with the Knicks. We watched him come back from a kidney transplant. We watched him mentor Dwyane Wade and Shaquille O'Neal to an NBA championship.

We watched Zo grow up.

Today, Mourning is that rarest of gems: a professional athlete with vision beyond the white lines.

He has matured from volcanic NBA center to thoughtful community leader.

He was all about winning. Now he is all about giving.

"I think my legacy on this earth will be service to others," said Mourning, whose foundations help the poor, the illiterate and the unhealthy.

When the topic of his future comes up, he has heard proposals of "Senator Mourning" or "Pastor Mourning."

"I can't see that right now -- plus, I got a mouth like a sailor," he said, smiling.

No, his intensity hasn't waned, but he knows how to channel it. His former coach, his old partner in workaholism, Pat Riley, hasn't seen such a transformation since Magic Johnson survived the crucible of his HIV diagnosis.

"Zo was so ultra serious, so committed, so over-the-top competitive," Riley recalled. "Earvin was playful, but also a winner and a killer on the court. He, too, went through a tragic event and look how it changed him.

"I call it the seed of equivalent benefit. I told Zo that to beat this thing you're going to have to back it."

We treat our sports stars like invincible supermen, and too often they believe it, but athletes like Mourning and Johnson learned how sudden the plunge from soaring to earthbound can be. Disease -- in Mourning's case, focal glomerulosclerosis -- made them more compassionate.

They became acutely aware of that clock Mourning refers to, the big, invisible one outside the Basketball arena.

"Sometimes it takes adversity to collect your thoughts and realize what your true purpose is," Mourning said.

He and Johnson have raised millions for medical research and for the inner cities of Miami and Los Angeles. They are spokesmen and activists. They've used their fame for the greater good.

"We still have a lot of work to do," Mourning said of himself and wife Tracy. "It's a disgrace to see the vicious cycle of illiteracy. We talk about children's problems when what we have is an adult problem."

He's had wonderful teachers: Fannie Threet, the foster mother who took him in as a confused and angry boy and taught him about the bounty of love; John Thompson, who taught him rugged self-confidence during Georgetown's "Hoya Paranoia" heyday, and Riley, the acidic motivator who taught him to carry himself with class.

Mourning decided to retire while he was in Washington, witnessing the inauguration of President Barack Obama. Lots of people approached him to ask, "How is your health?" It all got him thinking about a "new chapter."

His knee is intact after a long rehabilitation, but this comeback won't end with Mourning waving goodbye from center court, his No. 33 Heat jersey soaked in sweat. It will end quietly, on his terms, 13 months after he crumpled to the court and yelled, "It's over! It's over! It's over!"

Mourning, "the taproot" of the Heat, as Riley said, didn't go kicking at Jeff Van Gundy or screaming with fans, but joking with Tracy, who videotaped his announcement and asked the last question, about what he plans to do with his spare time. "I'll wash dishes and take out the trash, whatever you want me to do, dear," he said.

Dear? It was the ultimate confirmation of what Zo called his "Jekyll and Hyde" transformation. The grouch grew up. The great thing is, he's still growing.

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