Video report by ITV News Correspondent Geraint Vincent
These six smiling veterans have fought some of life's toughest battles - even after coming under attack from insurgents in dangerous war-zones.
As a group they experienced homelessness, attempted suicide, bereavement and survivor's guilt.
Now they are embarking on a 1,000 mile walk across America in a bid to help others.
Here they tell ITV News their remarkable stories of survival.
Kevin Carr - UK
Kevin Carr, 35, a former driver with The Royal Logistics Corps, found himself looking over the edge of a cliff after suffering depression following his medical discharge from the military.
His life began to turn around after a friend saved him from suicide and now, after confronting his problems, says he feels "privileged" to embark on the challenge.
Kevin wants to help relieve soldiers and veterans of the poor mental health that contributes to the 22 military suicides that occur in the UK every day.
He said: "I feel honoured and privileged to be part of this unique challenge and have the opportunity to help other veterans and raise awareness that there is support available – no-one should suffer in silence."
Adele Loar - US
Adele Loar's devastating war injury saw her lose her right eye when her vehicle was hit by an EFP (explosively formed penetrating warhead).
She also lost her partner Dan in the explosion and "lived in misery", thinking she was "insane" for four years until she was diagnosed with PTSD, TBI and depression.
Having received treatment she now wants to use the walk to highlight the help available to others suffering from mental disorders.
She said: "It is important people understand healing the outside physical wounds are sometimes a lot easier than coping with the emotional/mental injuries that are also sustained in combat."
Kemsley Whittlesea - UK
For Kemsley, taking part in the walk "is a mix of emotions" because, while he is excited to complete the expedition, he is also sad that it comes at the end of a 15-year military career that he "loved".
Kemsley, who served in the Royal Signals, said: "I hope to be able to meet up with some of my American friends from the US Army and US Marine Corps that I’ve served with in Iraq and Afghanistan.
He added: "More personally (I want) to remember guys I served with from the US that unfortunately never made it home."
Larry Hinkle - US
Larry Hinkle, who served for four years in the US Marine Corps, suffered "survivor's guilt" after his vehicle was hit while out on patrol in Iraq.
He was diagnosed with PTSD after leaving the military and found himself taking strong doses of painkillers and drinking heavily before he began walking for charity.
On the walk he says he wants to "spend some time with his British brothers and spread as much love as we can".
He added: "Hopefully the awareness can save some lives."
Frankie Perez - US
Puerto Rican Frankie, who signed up with the 92nd Manoeuver Enhancement Brigade in 2001, was struck by an improvised explosive device (IED) during his deployment in Iraq.
He spent the following 10 years suffering with PTSD and hit rock bottom when he attempted to take his own life, resulting in 30 hours incubation.
Frankie began volunteering for veteran organisations to help "with the ‘invisible wounds' sustained in and as a result of war" and says he is "honoured" to take part in the Walk of America.
Jonathan Burns - UK
After being medically discharged in 2016 due to shoulder injury and mental health challenges, Jonny, 28, began sofa surfing.
He had originally decided to join the Army to find a sense of identity, purpose and family, but after eight years of service he was unable to adjust to civilian life and found himself homeless.
By walking 1,000 miles through America he wants to "highlight the support open to veterans in the UK that may be suffering in silence".
He said: "Just because everything looks good on the outside does not always mean that everything is okay on the inside."
He added: "It is very easy to put a front up and pretend everything is okay but through my own experience I know that if these issues are unresolved, they do come back and cause problems later in life."
Every penny and every cent raised during the walk will be split 50:50 between military charities on both sides of the Atlantic.