The everyday runners among the 45,000 participants saw it as a challenge of a lifetime.
For some the goal was just to finish the race.
For others it was about running hard and fast enough to achieve their best time.
But regardless of the motivation for taking on a marathon, runners had plenty of support along the way.
It was almost too much for Filomena Kulesza as she cheered on her good friend, a second-year marathoner.
"She's a great friend, she's a lifelong friend, she'll be a lifelong friend foreverThere was excitement along every mile of the 35th running of the Chicago Marathon.
Management consultant Bruce Beabis picked up his bagpipes to serenade the fleet footed.
"Pretty much everyone that goes by waves or shouts at least smiles," he said. "It's kind of fun to do this."
Beabis's 13-year-old daughter and her friend hoped to encourage runners with a performance.
"We thought it would be great to inspire everyone," Katherine Beabis said. "It's just fun to do and make everyone smile."
And that it did.
"It's like a runners high when you have no more adrenaline left," said runner Natasha Ratliff. "Someone's there to give you a shot in the arm and say you can do it. You can make it."
And the reason why Buffalo Grove native Wanda Tyndall-White plans to complete her 11th race.
"I'll be 63 in a couple of weeks so I have to keep moving," said runner Tyndall White.
Sunday, some 45,000 elite and amateur runners traveled the 26.2-mile course enjoying the unique sights and sounds in 29 of the city's different neighborhoods.
For Karen Sanderson, the competition was not only about achieving her personal best of 4 hours, 8 minutes, but also about the support of a city along with family and friends.
"It's always wonderful just to know that she finished," said Sanderson's father, Stanton.
"He's been here every marathon that I've run," Karen Sanderson said. "It's really nice."
Sanderson finishes in her best time, as did Sandy Moreira, who came up form Indianapolis with her husband for the race.
"Chicago is a wonderful city,' she said. "It's a nice flat course. The best weather and the crowd are great, the crowds were fantastic today. And you have good food before and after."
Personal records were helped a lot by the cool temperatures.
On warmer race days, runners are warned to slow their pace and take good care of them on the course.
Sunday, there was no heat-related caution.
And for those who trained in the Chicago area, they were ready for a truly October day.
"The other factor is (Saturday) and last couple of weeks, especially in the Chicago area, we've had cool Saturdays and Sundays, where our general participants do their training and they've had a chance acclimate themselves," Pinkowski said.
While visits to medical tents were down by 60 percent, 10 were runners who were transported to local hospitals, including one man who had a cardiac incident.
"The individual was shocked twice and became alert, and talking and was transported to the nearest hospital," said Marathon Medical Director Dr. George Chiampas. "Our latest update is that he's alert and talking with emergency room personnel,"
Many of the amateur runners say they are already feeling the effects of running 26.2 miles.
They add that it was well worth the sense of accomplishment they feel.
That along with the fan support has most planning on doing it again next year.
Marathon organizers are looking into why they ran out of medals.
Sometime after the 7th hour, runners were not receiving their medals when crossing the finish line.
A spokeswoman for the marathon says 1,300 finishers will get their well-earned hardware.