MAMARONECK, N.Y. — Robin Nesdale’s story is not that unusual. At 56, divorced and with her daughter, her only child, off at college, her life felt a little empty and rudderless.

Friends suggested that she take up a hobby or volunteer at a local charity, but “that didn’t suit me,” Ms. Nesdale said. “I’ve always been a tomboy.” And then one day, she passed the local fire department in Mamaroneck, where she lives, and saw a firefighter sitting outside. They chatted a bit, and “I asked him, ‘do you think I could do this?’ and he said, ‘Sure.’ And it was like a light bulb went off. I wanted something to help me and the community.”

So she put in an application to become a volunteer firefighter.

That was just about a year ago, and in a ceremony on Thursday, Ms. Nesdale will graduate as a volunteer firefighter. Walter Ferguson, a state fire instructor in Westchester County, said Ms. Nesdale was the oldest woman to become a volunteer in his 20 years as a teacher.

That meant Ms. Nesdale had to, among other things, complete 130 hours of class time and pass two 100-question exams and a written hazardous-material test, as well as a physical test that would challenge someone half her age.