On Monday, thousands of athletes from across the world will run in the Boston Marathon, but you may not be familiar with another long-distance event with close ties to the marathon happening the day before. 

Strapped with a backpack weighing 20 or more pounds, participants of the annual Tough Ruck march in memory of fallen service members and first responders, while also raising money for their families. 

Participants who cross the Tough Ruck finish line receive the same medal as athletes who run all 26.2 miles of the Boston Marathon. Some, like Command Sgt. Major Bernie Madore of the Army National Guard, have completed both. 

"The day started out as one of the best days I've had in the military," Madore said. "As we cross the finish line, there's nothing like finishing in Boston with the crowd. And then we're right there when the first bomb went off."

Moments after the triumph of crossing the finish line, Madore and his friends ran back toward the scene of a horrific attack. They pulled back the fencing lining Boylston Street and began to render first aid. 

"What was amazing that day was the response of the first responders," Madore said. "I remember I was doing what I could, and as I was applying tourniquets, I looked up and the people were already being taken care of by medical staff."

Madore has said taking part in the Tough Ruck helps him deal with the memories of being at the Boston Marathon bombings, and remember everyone impacted that day. 

For him and all of the other military members, first responders and civilians who now make the 26.2 mile Tough Ruck march, each step is personal. 

"I think about how my family would be impacted if I didn't make it back," said Jesse Richardson. "To me, the fact that at the finish line, it's a Gold Star family member, Gold Star son, Gold Star sister, Gold Star mother, staying connected for them, that's what I would want for my family also."

Richardson and his friend Sean Douglas are both Army veterans, and traveled from Hawaii and Maryland for the Tough Ruck. They do it to honor fallen friends, and ever since their first trip in 2018, they knew they'd be back. 

"The night before, we sat and talked about things that we had gone through and people we had known," Douglas said. "Therapeutic is the right word, but it doesn't feel like it's enough. We come out here, and we can feel our people with us."

Participants raise money for the Military Friends Foundation, which aims to help loved ones of those who gave the ultimate sacrifice. The foundation and the Tough Ruck event itself inspired Richardson, Douglas and several others to launch their own charity called Send Me Outdoors, which aims to connect veterans with outdoor recreation opportunities to support their physical, mental and emotional well-being. 

"We've started doing events, we've started engaging in a different and very deliberate way with our community," Richardson said. "This is one of the events our charity sponsors to get family members up, some Gold Star family members and some guys in our community we want to keep engaged."

This year, the Tough Ruck fundraising effort has been quite successful. Jason Hedly is participating with his brother James and father John, all of whom served in the military. 

"Our goal was $ 450 each," Hedly said. "As of this morning I looked, I'm almost at about $1,000, my brother is about $1,000, and my dad is at about 1,500."

Showing up every year for Tough Ruck helps competitiors find others who understand what they've been through. Madore said everyone has a story that brings them to the starting line. 

"Everyone's doing it for a reason, they're not just doing it to win a medal," Madore said. "They're doing it to support someone, they're doing it for their fallen people, and it truly hits home."