When Sharen Duke turned 40, she decided to do something momentous to commemorate the occasion, so she ran the New York City Marathon. That was 10 years ago, which means she turned 50 this year and—what a surprise!—she’s once again celebrating a significant birthday with a 26.2-mile jaunt through the five boroughs.

A lot has happened in the intervening years. Sharen’s daughter, Alina, who was 2 years old and dozing in her stroller during the race in 2000, is now 12, and she has two brothers, 5-year-old twins Sammy and Rashi.

“Part of what motivated me to run this year was that with three kids and a full-time job, it was really hard to fit in fitness,” she says. “I wanted to lose my pregnancy weight, and I was a little freaked out about turning 50. So in 2009, I ran my nine races and did my one volunteer and got my automatic entry.”

Duke is the executive director and CEO of AIDS Service Center (ASC), a non-profit she co-founded 20 years ago to help people with AIDS in Lower Manhattan. Today, the Center has four sites, a staff of 85, and $7 million worth of programming that serves the HIV-positive community, providing counseling and testing, medical care, mental health services, and much more.

“At AIDS Service Center, our tagline is ‘Helping many, one by one,’” Duke says. “We say that each person has their own individual journey, and we want to create the environment that helps them move along the path that they choose one step at a time. That’s the way I’ve been navigating the responsibilities of home and work to create the time to do my runs, one mile at a time.”

To help her training, Duke joined the Front Runners New York team, which has partnered with ASC to create a fitness and wellness program for people with HIV/AIDS. When Duke toes the line on November 7, she’ll be running to raise money for that ASC fitness program. “The goal is to get people running,” she says. Then she smiles and adds, “Yeah, there’s a lot of intertwining between what I do at home and what I do at work.”