One year after Travis Snyder returned home from deployment in Afghanistan, a close friend from his task force died by suicide.
Snyder, 32, knew of the harrowing statistics of suicide among veterans, but his friend's death last April left him shocked.
"Before that, I read about it and had awareness but I didn't fully understand the magnitude that this epidemic has on people," Snyder told ABC News on Thursday.
There were more than 6,000 veteran suicides in 2017, with an average of 16.8 per day, according to the most recent data from the Department of Veterans Affairs.
Snyder felt the need to help, so he came up with a plan: leave his job and apartment to start a mission to raise awareness.
He decided on walking around Lake Michigan for 42 days, and creating a Facebook page where he could post daily updates about the cause.
On Sunday, Snyder finished his walk with 810 miles under his belt and more than 3,500 people following his journey on Facebook.
"I'm still getting messages and phone calls from people who just want to talk and share their story," Snyder said. "Just when I think I understand the magnitude, I learn more."
During his walk, which he began in Manistee, Michigan, he averaged about 20 miles per day.
He planned to sleep outside each night, but was stunned by the acts of kindness that both friends and strangers offered.
"Every single day people were reaching out to support the cause whether it was a roof or a meal ... I did not sleep outside once," he said.
"I'm just glad that people have built a community together," added Snyder, who served in Afghanistan as a corporal from October 2017 to April 2018.
He hopes his mission will continue to make people "more aware of resources that are available to them and more comfortable to talk about suicide."
Just before speaking to ABC News, Snyder said he got off the phone with a woman from Michigan who lost a loved one to suicide two days before he began his walk.
He plans to keep the Facebook page open for that exact reason: so more people can reach him.
"I feel humbled and honored to share the burden of those who are still healing from losing a loved one or feeling the pain of someone going through challenges that they've been facing," he said.
Marine veteran walked 810 miles in 42 days for veteran suicide awareness