(NewsNation) — When Jim Milam left the Army after 17 years, he was left with wounds inside and out. In addition to a shoulder injury that rendered him unable to do some of his favorite hobbies, he struggled with PTSD and a traumatic brain injury. He rarely left his home.

But then a friend of his invited him to a dinner with a Florida-based nonprofit called Soldiers Freedom Outdoors. He got to know the group and eventually went on a retreat that the organization holds for veterans that includes a range of outdoor activities – from hunting and fishing to horseback riding.

“I just felt at home,” Milam said, recalling how the retreat eased his mind.

He chose to start volunteering regularly with the organization and eventually joined its board of directors so he could help other veterans explore “ecotherapy:” the healing power of the outdoors.

In recent years, ecotherapy and equine therapy, treatment involving horses, have gained traction among groups that work with veterans.

Last year, an organization called Rustic Warriors in Wisconsin started taking veterans on outdoor excursions similar to what Soldiers Freedom Outdoors is doing in Florida. Meanwhile, outdoor education organizations like Outward Bound have built out free programs for veterans with the intention of improving mental health.

A growing body of research shows that these organizations may be onto something. Studies have shown improvements in mood and reductions in stress associated with outdoor activities.

Veterans have severe mental health needs. The federal government estimates 7% of veterans will develop PTSD at some point during their lives. In 2019, there were an average of 17 veteran suicides a day.

Daniel DiMarco, who founded Soldiers Freedom Outdoors in 2011, was inspired to start the nonprofit when he watched a television program about veterans and special needs children going on outdoor excursions.

Soldiers Freedom Outdoors does not bill itself as a replacement for traditional therapy or treatment. But DiMarco wanted to find a way to help veterans who were struggling with their mental health, and the organization slogan is “healing the hidden wounds of war.”

DiMarco started by bringing veterans to his home, housing them in RVs and taking them out for horseback riding and other outdoor activities. As the organization grew, in 2013 they bought around 300 acres in Central Florida to build what they call Camp Freedom.

It includes a dedicated home for veterans and a large lake.

“It’s really their home away from home,” DiMarco said. “It’s a place they can come and relax. All the meals are home-cooked.”

A veteran’s retreat typically lasts four days.

The first day is dedicated to tour of the property and ice breakers. One the second day, veterans can choose any number of activities like horseback riding or hiking. But DiMarco emphasized that the choice of what to do is completely up to the veterans themselves.

“They can pick and choose what they want to do. I want them to relax. If they want to sleep until 9 o’clock because they need the rest, let ’em sleep. If they want to sit on the hammock and take a nap and watch the grass grow and relax, fine. But here’s a list of activities we have, you can pick and choose what you want to do,” he said.

The organization’s programs serve around 300 veterans a year. Rachael Sickenberger runs the one of those programs, which involves horseback riding.

She said that some of the veterans who don’t have experience with horses can be tense at first when meeting the animals. But the tranquil nature of the horses eventually soothes the veterans as well.

“You just walk up and just kind of get to see how calm they are and it just helps the people really relax — when they see how calm and quiet the horses are, they just kind of follow suit and relax with them,” she said.

Sickenberger pointed to the self-directed nature of the horse rides as empowering for the veterans.

“They’re like, ‘It was amazing. I got to do the ride not somebody telling me how to do the ride for me.’ And they just love it. I really don’t think I’ve had anyone who hasn’t absolutely loved getting to come out and go for a ride,” she said.

DiMarco said that he would like to expand the organization’s offerings in the future, but currently it is volunteer-run from top to bottom so time and money (drawn from charitable donors) are both constraints on what Soldiers Freedom Outdoors can do with veterans.

But he doesn’t think he would change the format of the retreats even if he had more resources.

“We do seven veterans at a time… It’s very personable. If you get too many veterans together, it’s not personable. You wouldn’t be able to spend time with all of ’em,” he said.

Milam only wishes he had learned about the organization sooner.

“There’s 26 miles from my driveway to their driveway and the 10, 15 years before I found ’em, or my friend told me about ’em, I didn’t even know they existed,” he reflected. “So I could’ve been down there a long time ago.”