Wheaton, Illinois (CNN) As a medic with the U.S. Marines, Bob Adams put his life on the line for his men in some of the most intense battles of the Vietnam War.

After returning home, he faced another devastating fight.

"The war followed me home," Adams said. "I began to drink more heavily and use drugs. And that would help sometimes with what I didn't know I had, which was post-traumatic stress."

Adams struggled for more than a decade -- enduring a stretch of homelessness -- before he got sober in 1985. By the mid-90s, he was a clinical social worker specializing in PTSD. He started feeding the homeless in Chicago and realized that many of the people on the streets were veterans.

"I began to see signs: 'Vietnam veteran. Will work for food,' " Adams said. "It was pretty clear that something had gone very, very wrong."

"Marines do not leave anyone behind. ... To see that code being broken shocked me into action."

Adams developed a plan to help, and his efforts gained momentum in 2004 when he met Dirk Enger, a U.S. Marine and Gulf War veteran who shared his passion. In 2007, they opened the Midwest Shelter for Homeless Veterans in a clapboard, single-family home that accommodated five veterans.

Today, the nonprofit provides nearly 400 veterans a year with free assistance, including housing and counseling.

The group's transitional housing program helps veterans for up to two years. Residents do chores, attend 12-step classes and spend four hours a day seeking employment or acquiring job skills. The five residents become a squad of sorts.

"We want them to take pride in their time in the military and remember what that was like," Adams said.

It's a formula that works. Adams says that about 80% of their veterans complete the program and rebuild their lives.

In January, Adams stepped down from his leadership role with the nonprofit, but he still visits two to three times a week. His devotion to this work runs deep.

"My Marines were my Marines. And these men who come through this house are my veterans," he said. "We don't leave anyone behind."

CNN's Kathleen Toner spoke with Adams about his work. Below is an edited version of their conversation.

CNN: Some veterans have said your transitional housing program is similar to basic training. Is that intentional?

Bob Adams: That is the idea. All residents work with a case manager and a therapist, but because everybody has been through basic training, including yours truly, I demand a high degree of discipline. Up at 6:30 in the morning, do your hygiene, get something to eat, do your chores, get to work at 9:00. If you don't have a job, you're on the computer, looking for something.

People don't sit around here all day, and that's a good thing. Every bit of it is done to get them moving forward in their lives. And it works. To watch people begin to change, to feel cared about, is beyond measure for me.

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CNN: Your nonprofit has expanded a lot over the last decade.

Adams: We now have two affordable housing homes, one for male veterans and one for female veterans. We also have permanent supportive housing for chronically homeless veterans and services that help veteran families either stay in their housing or be rapidly rehoused. And we have a free store where veterans can get clothing, household items and furniture.

CNN: In addition to the veterans on your staff, former residents also volunteer and drop by to visit.

Adams: One of the mottos of this place could've been "veterans helping veterans," 'cause that's truly what this has been. You get on your feet and then reach back to the people struggling behind you, to help them come along.

No one can say the things that need to be said quite like someone who's been there. The idea that these veterans want to be of service -- is there a better legacy than that for an old guy like me? I don't think so.

CNN: You've gone through so much, both during and after the Vietnam War. Is it ever difficult to see people struggling with these same issues?

Adams: I couldn't sleep at night if that were happening and I wasn't trying to do something about it. One of the great things about all that I've been through is that I can bring that (experience) to them.

All of my troubles I get to transform into a way to help people, to change their lives. And that's about as good as it gets for me.

Want to get involved? Check out the Midwest Shelter for Homeless Veterans website and see how to help.

To donate to the Midwest Shelter for Homeless Veterans click the CrowdRise widget below.