The love affair started in 1988 near the Los Angeles Memorial Coliseum.
Curious after hearing about the upcoming event, Alfredo Garcia Jr. drove to Exposition Park on a March day to see runners complete the third Los Angeles Marathon.
The then 35-year-old Garcia watched most participants finish the 26.2-mile race with smiles. He saw others shed tears. And they all collected medals.
Garcia had never run more than a few miles.
"I said to myself, 'You know what? I've got to do this,' '' he recalled.
In 1989, Garcia ran the L.A. Marathon for the first time. Last year, just before he turned 60, Garcia completed his 100th marathon, setting up his schedule so he could achieve the milestone at the race that ignited and continues to fuel his passion.
"I love L.A.," he said. "Pretty simple."
On Sunday, Garcia once again will be among more than 25,000 participants in an event that sold out for the second consecutive year.
The race starts at Dodger Stadium and ends in Santa Monica.
Sixteen elite men -- including defending men's champion Erick Mose of Kenya -- and 10 elite women will compete for as much as $75,000 in prize money.
But the spirit of the L.A. Marathon is the thousands of first-time participants, runners competing for charities and others such as the marathon-smitten Garcia, who lives in Lomita.
In 2016, Los Angeles will host the U.S. Olympic men's and women's marathon trials, a prestigious event that will be run on a course still to be determined.
But the L.A. Marathon will still be on the Stadium to the Sea course.
Tracey Russell, chief executive of the marathon, said "we love to create the stage" that allows "weekend warriors" and others to share the same start and finish line with some of the best runners in the world.
Garcia, a retired Air Force lieutenant colonel who works as a systems engineer for Raytheon Space and Airborne Systems in El Segundo, did not envision himself an athlete while growing up in Freer, Texas.
"I was never much of a sports guy," he said. "I was more of a brainy guy. A nerd."
Garcia said he earned a college degree in physics in 1974 and explored military career options because of a difficult job market for engineers.
It was during one of two four-year assignments at the Los Angeles Air Force base near LAX that Garcia heard about the L.A. Marathon.
Once he saw it, he was hooked.
He started reading books about marathoning and gave himself five months to prepare for the 1989 race. He ran one mile a day for five days, and slowly added mileage until he was completing eight miles a day, five days a week.
He finished his first marathon in 3 hours 43 minutes and 57 seconds.
"I got to the finish line with a smile on my face, they put that medal around my neck and that was it," he said. "I thought, 'I'm going to do some more.' "
After two more L.A. Marathons, Garcia pledged to complete 50 marathons before he was 50, a feat he achieved in 2003 in 3:51:48. He then aimed for 100 before he was 60, a milestone he reached last year in 4:52:39.
The 5-foot-8, 145-pound Garcia said he runs with "more of a really fast shuffle" that lessens impact. His laptop computer includes charts and graphics that record every day, week, month and year of workouts. He has logged more than 40,000 miles since he started.
Garcia has participated in all but one L.A. Marathon since 1989: In 1998, the race date fell on the wedding day of a previous marriage.
"The date was not negotiable," he said, chuckling, noting the venue for the ceremony in Tucson, Ariz., was available only on that day.
Before cellphone cameras existed, Garcia ran with a disposable camera and recorded his arrival at every mile marker. Now he uses his smartphone to post to his Facebook account during the race.
"I probably waste 20 minutes taking pictures and posting, but I'm not out there to prove anything," he said. "I'm out there to enjoy the experience."
When not training for or running marathons, Garcia said he and his girlfriend enjoy attending Comic-Con International in San Diego, and other cosplay events, in superhero costumes.
His daughter, April, said Garcia was "younger in spirit than half of everybody I know."
"He's shown me how to set a goal and keep it and go with it," she said, laughing. "But he takes it to a whole new level."
Garcia's home includes a wall where medals from all of his marathons are displayed. Last year, after he crossed the L.A. Marathon finish line, Garcia said one of his first thoughts was, "I just ran 100 marathons. That's cool. What's next?"
Sunday's race will be his 106th marathon. He has his sights set on completing 130 before age 65 and 150 before age 70.
And he plans to pass those milestones in Los Angeles.
"It's like your first love," he said. "I'm going to come back every single year."