The Daddy's Home star, 44, headed to the Revere Hotel Boston to meet the 68 members of Spaulding Rehabilitation Hospital's Race for Rehab team as they prepped for the 26.2-mile race on Monday.
Wahlberg – currently in Boston filming Peter Berg's Patriots Day, a retelling of the 2013 Boston Marathon bombing – entered the room to "I'm Shipping Up to Boston," by the Dropkick Murphys, alongside costar Michael Beach, who will play former Massachusetts Gov. Deval Patrick.
Wearing a blue sweatshirt, a Red Sox baseball cap, blue jeans, and work boots, the Boston native posed for photos with running team, and gave a passionate speech about his involvement in the film.
"Everybody knows somebody who was directly impacted by the bombings at the marathon, and what a horrible tragedy it was. And when they decided they were going to make this movie, they had come to me and asked me if I wanted to be a part of it, and I was like, I don't think it's a good idea," Wahlberg told the group, which included survivors Heather Abbott, Roseanne Sdoia, and police officer Dic Donohue.
"But then when I read the script then I realized, oh my God, this is so powerful and so inspiring and such a tribute to everybody: victims, the rescue workers, the police department, the FBI, everybody," Wahlberg said.
"I also realized that if I wasn't going to be a part of this somebody else was going to be ... and I didn't know if they would handle it and be as committed to getting it right as I would," he continued. "So, I figured, you know what, I needed to be a part of this and I am so glad that I did."
"I can guarantee every one of you guys that we are going to make every single person very, very proud, and that's what we're committed to doing," he said, adding:
"I pride myself on being able to come back and hold my head up high, and I want to promise you guys how committed I am – how committed we all are – to getting it right and making everybody proud."
Patriots Day also stars J.K. Simmons, John Goodman, and Michelle Monaghan and is based on a variety of sources, including first-hand accounts and news reports.
It is slated to open in theaters on Dec. 21.