It had been, he decided, quite a career.
Forced to sleep sitting up for a month after surgery performed by Reds medical director Tim Kremchek, the 39-year-old Zaun kicked around the idea of retirement during fitful nights of sleep. In all honesty, he didn't need a whole lot of convincing.
Zaun was, essentially, already there. And he had a job waiting for him, having served as a postseason analyst for Rogers Sportsnet in Canada since 2006.
"I had reconciled it in my mind," Zaun said. "After all, the odds of someone being interested in me at my age and coming off the surgery I had were slim, especially a team that was going to be competitive."
A funny thing happened, though, on the way to his easy chair and pension. Zaun's balky right shoulder, the one that failed him in 2010, responded well enough to treatment and rehabilitation that Zaun almost felt guilty about not giving it another whirl.
That brings us to today, where you can find Zaun dressing alongside the other catchers in the Padres' clubhouse. He's here on a Minor League contract with no guarantee that he will still be around when the team breaks camp late next month.
The Padres would like nothing more than for Zaun, who turns 40 on April 14, to perform well enough this spring to win the backup catching job behind Nick Hundley. In a sense, though, Zaun feels he's already won something.
"I am actually kind of glad that I went through this at this stage in my career," Zaun said, noting the aggressive rehabilitation program he endured to get back to the point where he could throw and swing a bat without pain.
"I had nothing to lose. I've had a nice long career, 16 years. I've got a World Series ring and a full pension. I'm not a 20-year-old kid who has a career ahead of him. I have had a nice run."
So why keep playing?
"I didn't want an injury to be the reason why I wasn't playing," Zaun said. "And I know I will be physically able to play baseball when Spring Training is over, whether that's here or elsewhere."
Zaun would prefer that place to be San Diego, even though he joked earlier in the week that he has more in common with some in the front office -- former players like A.J. Hinch, Brad Ausmus, Mark Loretta and Trevor Hoffman -- than he does with his new teammates.
Even if that means doing some mentoring with Hundley and, for now, the other catchers in camp who can't come close to not only his service time, but all of the experiences he's had over a career that began in 1995 with the Orioles.
Most of all, aside from winning a job, Zaun wants to be a part of a winner again. That hasn't happened enough, as far as he's concerned, during a career that has seen Zaun play for the Orioles, Blue Jays, Marlins, Royals, Astros, Rays, Rockies, Rangers and Brewers.
"I knew I was done with projects," Zaun said. "I didn't want to be part of a team that was rebuilding or just mentoring a young catcher or pitching staff. It's tough, because for the better part of 10 years, you're butting your head against a wall trying to help young guys take the next step.
"The game is changing. Kids are coming into the game now with a lot of money in their pocket and a big sense of entitlement. And some of them are hard to work with. I didn't want to do that anymore. I wanted to be on a winner. That's really the only reason I'm still playing. I want another World Series ring."
For any of this to be possible, Zaun needed cooperation from his shoulder. After surgery in June, Zaun was told the typical recovery process would last anywhere from six to eight months.
That eight-month mark is now, though his recovery hasn't always been without trouble.
"I feel great. I feel tremendous. It seems to be getting better, better and better," Zaun said. "I went through periods when I would get stuck with a certain [throwing] distance or strength or endurance level. When it happened, we would switch the workouts up and blow through those plateaus."
Zaun said there were hiccups along the way, including ones that occasionally made him wonder if he was going to be ready for Spring Training.
"I had another one three weeks ago, where it seemed like I couldn't get past 100 feet," Zaun said. "I was frustrated. I started throwing a weighted ball against a brick wall as hard as I could, hoping it would break up some scar issue. That happened, and now it seems to be doing better."
Ausmus, who retired last season after 18 years in the Major Leagues, is in camp as part of his duties as a special assistant to the baseball operations staff. You can find him working with the catchers in camp -- most considerably younger, but one who is exactly two years younger than him.
Is Ausmus, who played until last season when he was 41 years old, finding it surprising that Zaun is still getting after it?
"No," Ausmus said. "I think that Gregg likes to play baseball. I think that he still enjoys it.
"I think he's had a tremendous career. The first half of his career he was a backup catcher, and the last half of his career he's worked his way into a starting catcher. That's kind of rare. But Gregg has gotten better and has taken pride in becoming a catcher as much as a hitter."