RIO DE JANEIRO (Aug. 20, 2016) -- Three-time Olympian Staff Sgt. John Nunn soldiered through an assortment of body cramps to finish 42nd in the men's 50-kilometer Race Walk at the Rio Olympic Games.On a hot and humid day in Brazil, with temperatures rising into the upper 80s during the 31-mile race along an oceanfront course in Pontal, only 48 of the starting field of 67 competitors completed the race.Reigning world champion Matej Toth of Slovakia won the race in 3 hours, 40 minutes and 58 seconds, followed by silver medalist Jared Tallent (3:41.16) of Australia and bronze medalist Evan Dunfee (3:41.38) of Canada.Nunn, 38, a Soldier in the U.S. Army World Class Athlete Program who lives and trains in Bonsall, California, finished in 4:16.12 -- 35.14 minutes behind the gold medalist. Just past halfway through the race, he began to cramp."I went through halfway in 1 hour 59 minutes and felt comfortable with it and thought things were OK," Nunn said. "About 5K later, it felt like the wheels were falling off. I was able to hold a 5:30 [pace] the rest of the way in, but it just wasn't the 4:45 that I needed.""I never stopped, but I certainly slowed," Nunn said. "It just wasn't what I was looking for. It was just a rough day."Nunn said that the cramps were in his elbow, locking it up completely, his neck, and most critically, his hamstrings."A couple times I had to slow down because the cramps would get so severe I couldn't straighten the leg," Nunn said.The situation prompted Nunn, as he's done many times, to call on Soldier training to help him complete the mission.He said the Army teaches values in basic training that are still with you 20 years later."They break you down and they rip you apart and they build you up the way they want you. I remember being a kid going through it and just thinking, 'I want to quit. I don't want to do this.' but it just helps you to learn how to get through things in life that aren't fun."Nunn welcomes the opportunity to soldier through both the mental and physical challenges of the sport."I really enjoy the mind over matter," Nunn explained. "You're just fighting and fighting and you keep having to block out pain and push, but when you finish a 50K there's a sense of accomplishment that you can accomplish anything in life if you put your heart to it."When Nunn crossed the finish line and tried to break stride into a normal walk, he nearly collapsed and had to be placed in a wheelchair and iced down for a few minutes before walking away under his own power."My right hamstring seized up," Nunn said. "I thought I could walk and then it started seizing and I was going to fall over."Nunn, who plans to apply for the Army's physician assistant program, already is talking about the prospects of competing at the 2020 Tokyo Games at age 42."The Olympics is always a great experience to be a part of, I just wish the end had gone a little better this year," he said."You don't keep going just to keep making Olympic teams, you keep going because you believe you can get better," he said. "I would like to go to Tokyo. I feel like I'm better than this. I want that absolute perfect race when it finally just falls into place."I still would like to find that elusive perfect day."