Kristin Walsh finished in tandem with her cousin Erin Murphy. Kristin Walsh photo

The Dorchester Running Club was organized a year ago this weekend with just a handful of amateurs who were hoping to find strength and motivation in numbers. This week, the club, which helped dozens train through the worst winter in Boston history, is getting heaps of praise from some of the Dorchester runners who crossed the Boston Marathon finish line on Monday.

“I couldn’t have done it without them,” said Kristin Walsh, 41, who trained for her first-ever marathon with the DRC and ran on Monday with her cousin, Erin Murphy. The Dorchester women crossed the finish line together in just under five hours.

Walsh, Murphy, and their friend, Jill Byrne, raised funds for the Gavin Foundation, which helps men and women recovering from substance abuse. They printed up t-shirts that read, “Heroin Sucks,” and helped raise awareness for the epidemic that continues to challenge families and steal lives across the commonwealth.

“People were so generous. By yesterday we were over $15,000,” says Murphy, whose 25-year-old son Brian inspired her efforts to help the Gavin Foundation and another recovery program, The Answer House.

Murphy spent some time last weekend reading through messages from people who donated to her effort in memory of family members lost to heroin overdoses.

“The cause was personal to me and it was so meaningful. So many people were willing to talk about the struggles with family members – it was more fulfilling than raising the money,” she said. “I’ve never felt like I had much information. I was the mother who didn’t know who to call and was sitting in an emergency room not getting the right advice on what to do to help my son,” she said.

Murphy eventually did get help and good advice while volunteering for Mayor Martin Walsh’s campaign, and she connected with a network of resources that have helped Brian and her family immensely. She and her friends have since become devoted to giving back to programs like South Boston’s Gavin House that help families.

Murphy had never run until she learned about the Dorchester Running Club, which had formed out of the Mud House on Neponset Avenue in the aftermath of last year’s marathon. At the time, Murphy says, she could barely run from the Mud House to St. Brendan’s church without a pause. Among the club members were Sheila and Mike McCarthy, who ran with Team MR8 this year and last and were essential to starting the club.

“We thought it would be a good idea to run the South Shore half marathon last fall and when we all finished, I kept saying, ‘We should just keep training. We’re halfway to Boston,’ ” said Murphy. “Once we all found out that we got numbers for Boston in early winter, we decided to do serious training together.”

Little did the group know that the serious training would include long runs through the relentless series of storms that buried the region in snow and ice through the entire month of February. Nevertheless, they never trained indoors. “I’ve never run on a treadmill,” said Murphy. “We would just go out every Saturday and it seemed like it was always a Saturday when the snow was coming down. But we stuck it out.”

Dorchester Running Club gathered for a dinner on April 16 at 224 Boston Street: Pictured are Jenn McQuaid, Erin Murphy, Kathleen Joyce, Jessica Gogola Manning, Kristin Hoffman Walsh, Jill Ermanski Byrne, Meghan Goughan, Marie Murray and Kerrie Young and supporter Sheila McCarthy, who helped start the club.On a few occasions, the core members of the club were joined by other Dorchester runners who were running for Team MR8, which often trained together as a unit in the city.

Last Tuesday, on the second anniversary of the bombing attack, members of the running club and Team MR8 members ran together in a five-kilometer race in memory of Martin Richard. They put out an open invite on social media, and were joined by scores of neighbors who followed a course through the neighborhood that ended at the Eire Pub.

“That was a great night,” said Murphy. “We had decided that last week that we wouldn’t run as much. After that run, we said, ‘This is a good way to end the training; we’re ready for Monday.’ ”

On race day, about 30 Team MR8 and Dorchester Running Club members waited for a bus at Park Street station to take them to Hopkinton. When a bus bearing the number 8 pulled up, they took at it as good sign, and hopped aboard.

Even though the runners in Murphy’s anti-heroin club had been cleared to run their own race – and not partner up – she and Walsh ran side by side from start to finish.

Walsh said she never doubted that they would complete the run and she was confident going into race day.

“We did the Hopkinton to Boston College trial run a couple of weeks ago,” she said. “When I was running up Heartbreak Hill, I said, ‘This is nothing like running up to Hutchinson Field,’ ” a reference to the steep course up Milton Hill that the Dorchester club would navigate on their training runs.

Still, Monday’s rain and chilly winds tested the mettle of even veteran marathoners. “I kept thinking snow and cold would have been easier than blowing wind in your face,” said Murphy. “The best part was when I got the top of Heartbreak Hill and the college students at BC were amazing. I was like, ‘Thank God they were there.’ ”

Walsh said she was buoyed by groups of cheering friends who gathered in Newton and Brookline. Then, alongside her cousin Erin, she coasted through the Back Bay with huge crowds cheering them on. “Coming up to Hereford [Street] was the golden moment,” she said.

Murphy and Walsh say they hope to run Boston again next year. And they’ll join Dorchester Running Club members this Saturday for a one-year anniversary run.