"I want to wish Harry and Meghan the happiest of lives together," said ambassador Woody Johnson

Former Army Captain Prince Harry advised veterans set to embark on a 1,000-mile expedition across the U.S. to “take it slow and enjoy it.”

Speaking with Harry in London on Wednesday, “he was great and you can see the passion that he has for this project,” says Adele Loar, 48, one of three U.S armed forces veterans in training to undertake the Walk of America kicking off in L.A. on June 2. “He wished us the best of luck.” The coast-to-coast walk concludes in N.Y.C. on September 6.

In remarks on Wednesday, U.S. ambassador to the U.K. Woody Johnson noted that Harry would not be joining the Walk of America as “he’s embarking on his own special relationship.” He passed along America’s wishes to Harry and Meghan Markle, who will wed in Windsor on May 19.

“I want to wish Prince Harry and Meghan the happiest of lives together,” said Johnson. Later, he told reporters that Harry and Meghan’s wedding will be a “symbol” of the close friendship between the U.K. and U.S. “It’s going to be big,” he said. “It’s going to be unbelievable.”

Credit: CHRIS JACKSON/AFP/Getty Images

Prince Harry meets with members of the U.K. Walk of America team in London on April 11.

Referring to the relationship between the U.S. and the U.K, Johnson said, “It’s about as close as you can get, it’s like family. You can have squabbles here and there but at the end of the day you are family, so you agree on the important things. So this marriage is going to be another symbol of that.”

At the Walk of America announcement on Wednesday, Loar — who suffers from PTSD after losing her right eye, injuring her shoulder and receiving a traumatic brain injury in an attack in Iraq in February 2006 — said she hopes the walk will boost her healing.

“When you’re walking you get to do a lot more internal thinking, and you think about everything that’s going on with yourself,” she says. “I’m hoping I’ll get more insight into myself. When you talk with other veterans, you always gain.”

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Loar, from Narragansett, R.I., who lost her partner Dan Kuhlmeier and their security officer in the attack, says, “I know what I’m doing wrong, but I don’t know how to do it right. When you talk to other veterans you get to learn different methods that maybe will work for you and help you out as well.”

The walk is intended to help promote the mental health of veterans too – an extension of the royals’ Heads Together campaign. “Everybody looks at your physical injuries,” says Loar. I spent three months in the hospital and they made me look back to normal — but my brain injury wasn’t diagnosed or my PTSD for years.”

Prince Harry Launches 'Walk Of America' Expedition
Credit: Chris Jackson/Getty Images

Prince Harry at the Walk of America announcement in London on April 11.

The walk is being supported by the Bob Woodruff Foundation, and the charity’s executive director Anne Marie Dougherty praises Harry’s “authentic commitment.”

“We’re trying to keep finding ways to amplify the goodwill between our two countries,” she says. “Today was really important because His Royal Highness is lending that bright light – and he has consistently done that. It is up to us to make sure we do some good work with the attention we are able to garner. We will be able to raise more money and help more veterans.”

She adds, “It’s interesting how when you’re in the military the camaraderie of training together, deploying together and, in many cases, recovering together — that bond exists regardless. We have tried to build on that inherent camaraderie. [Harry] has first been a comrade and someone who is relatable and incredibly humble and authentically commited to really using the platform that he has to help other veterans.”

Although there are three Britons and three Americans, they are walking as a “joint” expedition in “one team, one fight,” says Loar.

“The Walk of America takes us back to our roots again. Challenging endeavours lie at the heart of Walking with the Wounded’s DNA demonstrating the resilience and determination of those who have served, highlighting the talent that exists within the veteran community,” said Ed Parker, co-founder and CEO of Walking with the Wounded.

The expedition will also raise vital funds for veterans both sides of the Atlantic. Every veteran taking part in the expedition faces challenges, and will have been physically, mentally or socially disadvantaged since serving. Two members of the U.K. team are currently homeless living in a veteran homeless residence supported by Walking with the Wounded.