William Shuttleworth, 71, of Newburyport, Massachusetts walked across the country for over three months. He told NBC 7’s Lauren Coronado he did it all for U.S. veterans.

Shuttleworth left Massachusetts on May 15 and arrived at his last stop in San Diego on Sunday.

An Air Force veteran himself, Shuttleworth said he wanted to raise awareness for veteran’s issues like suicide, healthcare and homelessness.

“To know that you can still do this at my age of 71 and do this for veterans… It’s pretty emotional,” Shuttleworth said. “It’s pretty honoring to be able to do this.”

His journey took him 3,600 miles or 10 million steps across the country. He said he wore out five pairs of shoes along the way.

Take a look at Shuttleworth's journey in the interactive map below.

Shuttleworth claimed the only items he needed for the trip were a 28-pound backpack with two changes of clothes and a tent.

“It was some tough times once I got to Blythe and El Centro. It was 114 degrees a couple days. It can melt you.”

“On the average day I burned about 7,000 calories. That’s a plate of lasagna, nine by 13. I can eat that every day and lose weight,” Shuttleworth joked.

When asked why he made the journey, he said, “Veterans were willing to put their life on the line for every breath of fresh air that we have. Don’t you think that’s worth a lot?”

As Shuttleworth finished his walk in San Diego, he was greeted by supporters and veterans from all over the U.S.

Shuttleworth added, “I can’t let these people down now. I have a mission to accomplish and I’m not going to let it go. I probably won’t walk across America again, but I can do a lot more by continuing my advocacy.”

William Shuttleworth said his next big project is to create a non-profit organization focused on veterans and homelessness.

Shuttleworth's website has more information about how to support his cause.