Josephine Smith, a legacy firefighter from the New York City Fire Department, finished the NYC marathon Sunday to honor her late father, Kevin Smith, who died while bravely serving during the attacks on 9/11.

Humankind, created by USA Today, put together a must-watch video of her journey to finish the race.

In the video, Smith, who joined the FDNY in 2014, explains how being a firefighter has changed her perspective on 9/11.

"It's almost like I can put myself in that position," she said, "you know, being a firefighter, being down there, looking at this going 'holy crap,' carrying the gear ... being on that back of a rig heading down there."

"I don't know if this sounds weird," she continued. "I look at 9/11 now, since I've been on the job, in a whole 'nother light."

The video goes on to say that though Smith is a legacy firefighter, as a woman, she still had a few challenges to overcome. Smith took the challenge in stride.

"'I gotta prove myself to the guys' and 'are they cool with a girl working here?' I was worried about that whole thing," Smith remembered. "You know, I've been there five and a half years now and I've completely proven myself, and these guys, they love me."

During the race, as Smith got closer to the city, her resolve grew stronger.

"Coming up the 59th street bridge — I got it. You start to hear the crowd. You hear everybody, and everybody is screaming," she recalls.

It wasn't all a complete grind for Smith, either. As she approached the end of the race, her FDNY housemates showed up in support and made her stop so they could buy her a beer.

Smith said she runs for our vets and their families, for her father, and for all those who passed away on 9/11.

Smith also ran the NYC marathon for the Stephen Siller foundation, which honors the sacrifice of firefighter Stephen Siller who laid down his life to save others on Sept. 11, 2001, and also honors the military and first responders who continue to make the supreme sacrifice for their country.