As a former British Army captain, Prince Harry has a special connection with his fellow service members.
Harry, who kicks off his paralympic-style Invictus Games for wounded warriors in Orlando on May 8, was a helicopter pilot on his second tour of Afghanistan in 2012-13, helping escort huge Chinook troop carriers that were sent to pick up the injured.
"Most of the flashbacks I've had have not been that brutal," he tells PEOPLE in an exclusive interview for this week's cover story. "I haven’t seen what other guys have seen. There's all sorts of things that can happen through your life, that if you don't deal with it, you don't talk about it, then it can end up affecting you in later life."
At the same time, he shares how helpless he felt during various points on his tour – and how it inspired him to launch Invictus.
During certain missions, "You think to yourself, 'Could we have got there quicker? Could we have done anything different?' Ninety-nine percent of the time not a chance. So you have Prince Harry in a $57 million aircraft in a helpless position. Then I come back and I say, 'How can I use my name and that spotlight to the best effect?'
"Going to Colorado and seeing the Warrior Games and being able to create the Invictus Games was almost like a cure for that pain that I had back then," he adds.
To read the full interview with Prince Harry, pick up the latest issue of PEOPLE, on newsstands Friday
Acutely aware of servicemen and women's loss, he sympathizes with those who've lost friends "blown up next to you . . . You have that guilt that it should have been you.
"Once you’re in that dark hole, that slide show is constant, one after the other. Those who do suffer from [flashbacks], we need to be able to help them. It’s not a life sentence, far from it. If we’re able to talk about it and give them the platform, then great."
Harry, who has become a powerful ambassador for veterans, has made the fight to help those with "invisible injuries" a center point of the work, alongside brother Prince William and sister-in-law Princess Kate, on mental illness.
A symposium on the efforts being made to aid those with Post Traumatic Stress or Brain Injuries takes place just before the games kick off on May 8.
"It is something that people talk about a little bit but need to understand a hell of a lot more," Harry adds. "But it is not something that just affects servicemen and women."
"If you have a sprained ankle, you go to [the emergency room]. There needs to be something for mental health."
Tickets for the Orlando Games can be purchased here.