The marathon holds extra meaning for some New Yorkers running on Sunday.
For Fort Greene resident Danielle Hacet, 31, running this marathon is a testament to her recovery from brain surgery in July 2015.
George Campbell, 63, runs in honor of his late wife, who ran the marathon in 1978.
There will be tens of thousands of runners on Sunday, and they each have different reasons for participating. Here's a look at four New Yorkers and what is driving them to the course.
George Campbell promised his dying wife Priscilla, who ran in the New York City Marathon in 1978, that he would run the TCS New York City Marathon in her honor.
While dealing with the stress of taking care of his wife, who succumbed to cancer on Feb. 6, 2013, Campbell's health deteriorated as well. His weight went up to 235 pounds, and he was eventually prescribed 14 medications for high cholesterol and other complications.
"When she passed, I decided to get back into the running game," said Campbell, 63, who lives in Fort George and is originally from Scotland. "I dumped the pills down the toilet and said that I am going to get my health in order."
After losing 80 pounds and getting a clean bill of health from his doctor, Campbell ran in the marathon last year for the first time.
"People asked me what I was going to do with my life after my wife passed," Campbell said. "I said, 'What I'm going to do with my life is get a life.'" (Credit: Photo courtesy of George Campbell; story by Nicholas Morales)
Having recovered from a July 2015 brain operation, Danielle Hacet will run her fourth TCS New York City Marathon on Sunday.
In 2012, Hacet, 31, of Fort Greene, started smelling smoke for no reason. But then an MRI found scar tissue on her brain from a bout of bacterial meningitis when she was 6 months old. It was causing her to have partial focal seizures. Three years and five medications later, her only remaining option was surgery to remove the scar tissue.
"I was so excited and so ready for surgery that I didn't prepare myself for recovery," Hacet said.
It took months for Hacet to regain her ability to walk and to heal from double-vision. She was finally able to start running in January and ran a half-marathon in April.
This will be Hacet's fourth time participating in the big marathon, but it's the most important so far because it signifies her recovery from brain surgery. It is her "comeback race," Hacet said.(Credit: Photo courtesy of Danielle Hacet; story by Nicholas Morales)
There is no obstacle big enough to keep some people from helping those they love.
Corey Zaretsky, who lives in Hell's Kitchen, will run in the TCS New York Marathon on Sunday to represent the National Kidney Foundation.
The 26-year-old donated a kidney to his younger brother, Matt, in August 2014. Matt was born with Nail Patella Syndrome, a rare genetic disorder that causes kidney failure.
In May 2013, 20-year-old Matt was diagnosed with pancreatitis, which led to kidney failure and called for the removal of his gall bladder, pancreas, spleen, appendix and part of his intestines.
Then Corey volunteered to donate a kidney to his brother.
"[It's a] major task for someone to have, but you will live the rest of your life knowing you saved someone's life," Corey said.
The kidney transplant was a success. Matt now lives a healthy life, only affected by diabetes.
In March, Corey decided to enter the marathon to raise awareness for organ donating. As of Thursday, he helped raise $11,120 in donations to the NKF. "If one person hears the message and decides to donate, it will make a huge difference," Corey said.
Donate at crowdrise.com.(Credit: Photo by Christian Miles; story by Anthony Payero)
For Rose Uscianowski, running 26.2 miles in front of thousands Sunday in the TCS New York City Marathon will serve as therapy.
Uscianowski, 27, runs to ease her bipolar disorder, which was diagnosed with when she was 16.
"I'm still [on] medication and go to therapy once or twice a month," she said. "I do much more than just run, but it [is] a part of my therapy."
While a student at Port Richmond High School, the Staten Island native struggled with mood swings and depression.
Uscianowski channeled her emotions into a positive: being active.
It was through a nonprofit bike tour three years ago that she found Transportation Alternatives, which she will represent in the race.
Uscianowski hopes to bring awareness to safety issues for cyclists and runners in the city, and is running despite being hit by a car in mid-September.
"Being able to finish and overcoming the crash will mean so much to me," she said.(Credit: Photo courtesy of Rose Uscianowski; story by Anthony Payero)