"I'm tired, I'm very tired. I'm so tired," David Letterman jokes with late night verve during an early evening phone call. "How are you?"Fine, thanks, but why so tired?"Well, I'm 68 years old, number one," Letterman says. "And number two: I'M 68 YEARS OLD."Minutes before, the abdicating king of late night heard another round of salty/sweet good-byes, taping The Late Show with David Letterman. Julia Roberts kissed him. Six thousand twenty-three pillow time talk shows down. Five more to go.Letterman's royal sendoff after 33 years of inventive television is deserved, if not preferred. For months, his staff told guests to lay off the farewell talk, at the host's request. Then the urge to pay tribute "started up like a furnace" and Letterman's staff told him to "just sit there and take it."Turns out it hasn't been torture."Like everything else, once I got a little bit of it I thought, 'oh, this is not so bad,' " Letterman said. "And it started to actually affect me."So I thought, well, let's see what nice thing this person has to say about me. You realize it's like a drunk: If one drink makes me feel great, what would a whole bottle do? Now when this is all taken away from me in a couple of days I don't know what will happen. I've grown to love it."I have something nice to add about David Letterman. Not about how he made audiences laugh, but how he made me cry. Why he's my fave Dave.Full disclosure: Dave and I have something in common, along with hundreds of thousands of other Americans. We're all members of the Zipper Club, living longer lives through open-heart surgery.The "zipper" is the resulting scar down the centers of our chests. Dave laughed in his heh-heh-heh way when I described mine as kind of like Ricardo Montalban in The Wrath of Khan. "You must've paid for the triple-A job," he said. "I didn't get the Ricardo Montalban chest. I think I got the Richard Simmons chest, I'm sorry."Fuller disclosure: David Letterman is the reason for my spirit-cleansing crying jag that doctors say to expect post-op.Cooped up at home, I found clips online from the Feb. 21, 2000, Late Show when Dave returned from quintuple bypass surgery, lining up the entire medical team to take bows. Then his interview with Barbara Walters, another Zipper Club member. The anniversary anecdotes he'd spin on the show. Dave handled his surgery the way I needed to, with humor and humility. I watched them repeatedly.But that isn't what made me cry.That didn't happen until I returned to work, stopping by the desk of Gretchen Letterman, Dave's sister and a former Tampa Bay Times editor. Spontaneously sobbing, I explained how her brother inspired me and asked a favor: Tell Dave thank you, please. Within days, he e-mailed a kind, modest reply.Two and a half years later, Letterman spoke to me at length about what the open- heart experience means to him."Personally, what it did for me was it reawakened what should never have been taken from me, and it was what I did," he said. "It restored my faith in human beings."I just assumed that if you're going to let yourself have open-heart surgery, it was going to be a flip of the coin, if you would survive or wouldn't survive. What I realized was, yeah, you're going to survive because the men and women doing these things know exactly what they're doing, they do it all the time and they care about what they're doing."So, for me that was a re-statement of something I had lost somewhere, which is: Yeah, people can do amazing things, they do it all the time, and you can have faith in your fellow man. So, that was good."More tangibly, Letterman noted his marriage to Regina Lasko and the birth of their son, Harry, happened after heart surgery. His co-owned racing team won the 2004 Indianapolis 500 in his beloved home state. In recent years, Letterman has been an annual visitor to St. Petersburg, joining the Rahal-Letterman-Lanigan team at the city's Grand Prix."Everything good that happened to me since then, I would've missed if I had dropped dead before they got me on the table," he said.Making more memories with Harry, 11, is a big reason Letterman is retiring. They're heading back to the Indy 500 later this month, spending time at their Montana home, fishing in the summer, skiing in the winter. "We want to go bonefishing," Letterman said. "That's one of our goals."The big difference is: Now my schedule will not be the overriding determinant of what we do and how we do it."Still, Letterman admits to having second thoughts along the way to Wednesday's concluding Late Show."Yeah, there's been back and forth," he said, "but I'm pretty sure that once it's finished there will be a time of introspection. Then I think I will relax into what would be kind of a normal life."One that's well-deserved. Thanks again for all the laughs, Dave, but especially for those tears.Contact Steve Persall at [email protected] or (727) 893-8365. Follow @StevePersall.