"I don't have a problem discussing it," he said. "It's part of who I am. Years ago, I might have wanted to hide it. The whole thing now is to remove the stigma and let people know there's hope."
Along with Harrington's awakening with regards to substance abuse is the effort he undertook to lose some of the weight he'd put on since his 1999 graduation from Malden Catholic High School.
"My wife (Danielle) got pregnant twice, and each time I guess I got pregnant, too," said Harrington, 37, referring to the weight he accumulated while his wife was carrying daughters Faith and Marley.
As a pipe fitter for Columbia Gas of Massachusetts, he finds himself climbing stairs every day for his job.
"I had to climb four flights of stairs in an apartment building, and by the time I got to the top, I was out of breath. Now here I was. I was an athlete in high school, and I couldn't climb four flights of stairs without getting out of breath."
The 6-foot-3-inch Harrington figured he'd jolt himself out of his malaise by running a road race. He took to social media and found a half marathon at Disney World in Florida and vowed to lose the weight and run it.
"It took me eight solid months to lose the weight and get in shape for it," he said. "It didn't take me too long to lose the weight. I dropped 60 pounds. I incorporated weight training and reeled in my diet."
He also said he rediscovered the instincts that made him a basketball player and a sprinter in high school.
"Plus, for me, it was peaceful," he said. "It was a reflective time for me. When I train, I put the Rolling Stones on my earphones and think of my dad (who died last year). I have the prayer card from his funeral mass, and I held it up as I crossed the finish line in New York last year. I'll do that again in Boston. Running has been a big part of my healing process."
He made it through the half-marathon and then signed up for the New York Marathon last November, and was accepted as a runner for the Chris Herren Project, a non-profit recovery program founded by the former Durfee High star who himself has battled addiction.
"My dad and I used to go see him play all the time," said Harrington. "Chris is really a good guy."
Harrington made it through New York, and while he generally runs for the Herren Project, he will be raising money for the Pine Street Inn Monday in Boston.
While he's been diligent about training, he says that things have been a little rockier than he'd like. But not for lack of effort or interest.
"Last October was the Merrimack Valley (gas) explosion," he said, "and we were all out straight. We were working like 90 hours a week and I had to fit (training) where I could."
Two weeks ago, he ran the course from Ashland to the finish line, and learned that "you can't go out too fast. The first part of the race you're losing elevation, and it's not until Newton that you hit the hills."
Running the race has paid huge dividends. For one thing, his wife has become a fitness instructor too, "and she's very supportive. She makes sure I'm able to get my training in. We work well as a team."
The other thing?
"I'm 37 years old, and I feel as if I'm in better shape than I was when I was 17," he said. "It's been a great time to think, and laugh, and cry. I'm outside, and it's been really, really good for me. It's been a big part of my recovery."