PHOENIX - For anyone who's run a marathon, they know just how tough it is. A U.S. Marine veteran of the wars in Iraq and Afghanistan just upped the degree of difficulty by about 100 percent.

Rob Jones, 32, was a combat engineer whose primary responsibility was clearing dangerous objects from the path of advancing troops. In 2010, while on duty in Afghanistan, he stepped on a landmine. The explosion cost him both of his legs just above the knee.

Once off the battlefield, Jones adopted a new mantra: Survive. Recover. Live.

Since he began rehabbing from the injury, he has mastered the use of his prosthetic legs. He became a member of the U.S. Paralympic Team and earned a bronze medal in rowing at the 2012 London Paralympics -- and he just missed out on a return to the Games in 2016.

Jones then set out to pay back all the goodwill he's received over the years.

On Oct. 14, 2013, he began a solo supported bike ride across America which started in Bar Harbor, Maine, and ended in Camp Pendleton, California. The ride was 5,180 miles long and wrapped up on April 13, 2014, a total of 181 days after it began.

Over the course of the ride, Jones raised more than $126,000 for the Coalition to Salute America's Heroes, the Injured Marine Semper Fi Fund, and Ride 2 Recovery, three charities which aid wounded veterans.

His drive to continue serving his fellow service members has blossomed into a new challenge.

"My goal is 31 marathons in 31 days in 31 different, major cities," Jones said before taking off on his 20th marathon run with about a dozen runners in tow along the Grand Canal in central Phoenix.

Jones' mission is multifaceted this time around. His primary goal is to continue to improve his own health and wellbeing, as well as that of his fellow Marines, soldiers and airmen.

"I hope to raise awareness concerning the struggle of America’s veteran population," Jones said.

And as he ticks off the miles on a course that will eventually end at the Mall in Washington, D.C., Jones says he hopes to prove to the able-bodied world that a wounded veteran still has an immense amount of value in the 21st century.

"It does not mean that they are broken or incapable of continuing to contribute," Jones said. "I'm just trying to add one story out there of a guy who went to Afghanistan and had a traumatic experience and was still able to figure out his new way to contribute to America."

He's been sharing his story for the past three weeks on a trip that started in London, and has taken him and his team across the U.S. to the Northwest and south to California and Arizona. At each stop, he says, he feels more and more encouragement for all U.S. veterans.

"Each city, I have at least 30-40 people that come out and support me, proving that veterans aren't alone, and there's plenty of people out there that want to help them," he said.

To support or contribute, visit Jones' website.