Max Rohn is on a mission to reclaim Invictus Games title

ORLANDO -- More than 500 athletes from 15 different countries are in Orlando, Florida, to compete in the second running of the Invictus Games, which Prince Harry launched from London in 2014 for wounded service members from across the globe.

Max Rohn is on a mission to reclaim his discus and shot put title atop the Invictus Games medal stand.

"Hopefully this year I can come out, put together a good performance and just out-throw the entire competition," Rohn told Norah O'Donnell, "CBS This Morning" co-host and Invictus Games ambassador.

That's a high bar, considering he wasn't always much of an athlete.

"I would say I was a bad high school athlete. I went to track and field at the first four year games; my coach always says you can't teach tall, so I was the perfect fit for throwing," Rohn said.

"Meaning you had the size?" O'Donnell asked.

"I had the size to be a thrower, which was comforting but also disappointing at the same time because I thought I was a runner and I was very fast. Turns out I was very slow," Rohn said, chuckling.

Though Rohn once lacked prowess on the playing field, he set out for a career on the battlefield.

"Primarily, what our mission was to go into police stations, look after the Iraqi police officers, train them with them help of Iraqi police advisors, which are just American cops," Rohn said.

Deployed to Iraq in January of 2009, he was seriously wounded by an insurgent-thrown grenade just five months later.

"What did you think when you knew you were injured? What went through your mind?" O'Donnell asked.

He said his first thought, just like any other corpsman in his position, was "Is everybody else alright?' ... That's when I looked down at my leg I was like, 'Alright, well, I'm not okay, so should probably fix that.' The Marines basically saved my life that day," Rohn recalled.

"You had been spending a lot of time saving their lives," O'Donnell asked.

"Well, I'd like to think that it works both ways," Rohn said.

The Navy corpsman spent the next four years as a patient at Walter Reed National Military Medical Center, where he received his Purple Heart, met President Obama and endured 14 surgeries to save his leg, before requesting a 15th to remove it.

"How hard was that decision?" O'Donnell asked.

"It wasn't very hard for me. I knew it right away because where I am at Bethesda, there's a lot of traffic. ... Most people going through limb salvage do not have good quality of life... You can either keep your limb and be in pain and you can't ever do what you wanted to do in life, or you can get the amputation and get your life back," Rohn said.

The first step to getting his life back meant hitting the gym. Within a year he entered the Warrior Games, a competition among U.S. military personnel who have endured injury.

Prince Harry was there, too. The Warrior Games inspired him to create the internationally-focused Invictus Games in 2014.

After its London debut two years ago -- and a lopsided medal count in favor of the U.K. -- the games have come to the United States, where Team USA is looking to turn things around, just like Rohn.

Rohn now spends 20 hours a week training in a Penn State University program designed for disabled athletes, which has him accomplishing more than ever.

"I'm in the best shape of my life right now," Rohn said.

"I'm a far better person after this life experience. Things go wrong. Stuff happens... It's what you do internally to deal with those problems," Rohn added. "I'm a stronger person for it, at the end of the day."

"You're living your best life," O'Donnell asked.

"Absolutely," Rohn said.

The opening ceremony begins Sunday, but a parade of athletes will unofficially kick things off at Disney World later Friday.

Watch Norah O'Donnell's interview with Britain's Prince Harry Monday on "CBS This Morning."