That dream became a reality in 1989, when Girardi, a Peoria, Ill., native broke in with his favorite boyhood team.
And as a catcher in his 30s, Girardi decided he wanted to eventually become a Major League manager.
Another personal milestone will take place for the 41-year-old on Monday when Girardi experiences his first Opening Day as a big-league manager.
The first-year Marlins manager admits he will experience his share of butterflies during the pregame ceremonies against the Astros at Minute Maid Park.
As a player, Girardi was part of three World Series title teams with the Yankees. He now takes over a youthful Marlins squad that projects to have an Opening Day lineup with an average age of 24.4 years old.
"They're going to have butterflies," Girardi said of his youthful squad. "If they don't, something is wrong.
"To be successful, you have to have confidence that you can do what you want to do. At 8 years old, I wrote an essay that I was going to play for the Chicago Cubs. Now that was probably a little bit premature. My senior year in high school, I believed I could play in the big leagues. Part of that is being naïve, and it's dreaming. It's the thing that motivated me, but I really wanted to do it."
That same drive is pushing Girardi as a manager.
"I wanted to do it for a while," Girardi said. "I've always imagined I'd get here. I didn't know that it would be this quick. I always believed I would get here."
Grapefruits for all: When the Marlins won the 2003 World Series title, owner Jeffrey Loria awarded his team one of the largest championship rings in professional sport.
Now that the Marlins won the Grapefruit League title, sporting a 19-9 mark in Spring Training games, Loria presented his club with a fitting reward: Grapefruits.
"When you win the Grapefruit League title, you get grapefruits," Loria said on Sunday afternoon.
More than 30 bags of grapefruits were sent out to the players and Girardi.
By percentage points, the Marlins finished ahead of the Reds in the final Grapefruit League standings.
The Marlins had a .679 winning percentage, compared to the Reds' 22-11 mark (.667).
Stadium stalemate: Opening Day begins for the Marlins on Monday with an uncertain stadium situation in South Florida.
Exploring relocation options, officials from San Antonio will be at Minute Maid Park on Monday as guests of Loria.
San Antonio is making a strong push for the Marlins. Meanwhile, talks for a new stadium in South Florida have been slow.
Addressing the stadium situation briefly on Sunday, Loria said: "It will get settled one way or another. ... We're still looking at all our options. But our talks with San Antonio are serious."
The Marlins plan on visiting more cities as a possible new home.
"We are also going to visit some more cities," Loria said. "We're going to make the best decision for the team. We're going to keep looking."
The Marlins initially visited San Antonio in December. Team officials also have traveled to Portland, Ore., and had a meeting in South Florida with representatives from Norfolk, Va.
"I can only tell you at this moment there is nothing going on in South Florida," Loria said.
Jacobs cleaning up: After being called up by the Mets late last season, Mike Jacobs made 100 Major League at-bats and finished with a .310 batting average with 11 home runs and 23 RBIs.
Now the projected cleanup hitter for the Marlins, Jacobs enjoyed a strong Spring Training, collecting 75 at-bats (a club high) while batting .307 with three home runs and 13 RBIs.
Early in Spring Training, Jacobs said he needed about 100 at-bats to be ready for the season.
"I feel like I'm where I need to be," the first baseman said. "I'm peaking at the right time."
Being in the Opening Day lineup will be special for Jacobs, especially seeing the Astros being honored Monday for reaching the World Series last October.
"Hopefully, we'll have some motivation," Jacobs said of the Astros' ceremony. "That's what we're here to do. We're here to win. The ultimate goal for every team is to win a championship."
On a retooled team, Jacobs is expected to bat fourth, where he assumes the role of protecting Miguel Cabrera, who likely will bat third.
"Obviously if I was in another lineup, I'd probably not be the cleanup hitter," Jacobs said. "So for me, personally, it's kind of an honor. I'm glad they feel confident in me to put me in that position. For me, it's just exciting to be in the big leagues opening up. Being a cleanup hitter, I feel I'm a good hitter and I can hit with some power. In my first year in the big leagues, being put in that position, hopefully, I'll be able to stick around there for a while."
Dressing 11 rookies: The baby-faced Marlins are carrying 11 rookies on their Opening Day lineup. Based on research done since 2000, that's the most rookies on a first-day roster since the Rockies (2005) and Tigers (2003) each carried eight.
The rookies are Josh Willingham, Hanley Ramirez, Jeremy Hermida, Jacobs, Dan Uggla, Reggie Abercrombie, Eric Reed, Chris Resop, Josh Johnson, Ricky Nolasco and Carlos Martinez.
Of that group, Monday will be the first Major League game for Uggla, Abercrombie, Reed, Nolasco and Martinez.
Nolasco felt he had a chance to break with the club soon after he was acquired as part of the Juan Pierre trade with the Cubs in December.
"It's a tremendous feeling," Nolasco said. "I'm sure when I'm out there [Monday] that it will be something I never forget. This whole offseason, since the trade happened, I just tried to give myself the most honest chance to be here. Even if I got sent down, I wanted to make sure I made a good showing. I never said I know I'm going to make the team, but I never doubted myself."
Coming up: Ace Dontrelle Willis, the runner-up in the 2005 National League Cy Young Award, gets the nod on Monday at 7:05 p.m. ET against Houston's Roy Oswalt at Minute Maid Park.
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.