(TNND) — Veterans are on a 100-mile hike in support of their brothers and sisters suffering from post-traumatic stress disorder.

“The goal ultimately is to raise awareness for PTSD and suicide prevention, spread awareness, and let veterans know that you're not alone,” said John Shafer, himself a former Marine who suffered PTSD following nine years of service and several combat tours in Iraq and Afghanistan.

“A lot of people struggle, myself included,” Shafer said. “So, it's a rough journey. Regrettably, I've tried taking my life on two separate occasions, because I felt lost. And I just felt like life wasn't worth living anymore. And so, coming and being part of events like this ... allows me to have that fulfillment, that sense of pride that I do matter.”

Shafer is one of a dozen people hiking from Wednesday to Sunday in Southern California to benefit Semper Fi & America’s Fund, a nonprofit that supports critically wounded, ill, and injured veterans, including providing assistance for those with PTSD.

This is Semper Fi & America’s Fund’s sixth annual "PTSD Century Hike," and it’s the third one Shafer has joined.

Shafer suffered multiple traumatic brain injuries from explosions during his deployments and was diagnosed with PTSD following his return home.

“PTSD is real, and oftentimes you don't even know what the individual's undergoing,” he said Thursday by phone while walking from Oceanside to San Diego.

He said PTSD is different for each person, but military members don’t always have a smooth transition to civilian life.

Shafer said he was almost homeless at one point. But Semper Fi & America’s Fund helped him, and now he wants to help others.

Shafer said he found hope in the PTSD Century Hikes, and he hopes the benefits ripple to other veterans in need.

“One person affected here goes back and changes one person, and then so on and so on,” he said. “And so, by the end of it, 25 lives been impacted from one event, hopefully making a change for the positive.”

HELP HERE: How to support the hikers or donate to Semper Fi & America’s Fund

Shafer said Semper Fi & America’s Fund helped restore his accountability to himself, to his own care. And he said he’s in a good place now.

“Keep pushing,” he said. “And that's what this hike symbolizes, you know, is that together we're stronger.”

If you or someone you know is having thoughts of suicide, contact the Veterans Crisis Line to receive free, confidential support and crisis intervention available 24 hours a day, 7 days a week, 365 days a year. Dial 988 then Press 1, chat online at VeteransCrisisLine.net/Chat, or text 838255.