SAN ANTONIO -- U.S. Army World Class Athlete Program Staff Sgt. John Nunn earned a berth in the London Olympic Games by winning the 2012 U.S. Olympic Team Trials for 50K Race Walk with a time of 4 hours, 4 minutes, 41 seconds in Santee, Calif., on Jan. 22.

Nunn, 33, of San Diego, surged during the final 1 ½ kilometers to shake Tim Seaman, 39, a two-time Olympian from Imperial Beach, Calif., who finished second in 4:05:50. Ben Shorey, 29, of Kenosha, Wis., was third in 4:17:30.

Because none of the athletes met the Olympics "A" standard of 3:59, only Nunn earned a berth in the 2012 Olympic Games in London.

"Yesterday was the greatest day since Athens," Nunn said via telephone on Monday, referring to his Olympic debut in the 20-kilometer race walk at the 2004 Olympic Games in Athens, Greece. "Yeah, I crushed them."

Five walkers stuck together through 20 kilometers before one fell off the lead pace. At 32 kilometers, another dropped off. At 36 kilometers, Shorey lost contact, leaving Nunn and Seaman to battle it out. With 13 kilometers remaining, Nunn opened a 50-meter lead with a move that almost backfired.

Nunn said his energy wavered as he neared the 41-kilometer mark.

"I was like, 'Oh, no, I don't have it,'" he recalled. "My head started getting light. My arms felt like all the blood was rushing out of them. I was thinking I might pass out."

Three kilometers later, "Tim passed me like I was standing still," Nunn said. "And I was like, 'That's it. All this work, I can't get it back.'"

Seaman built a 25-meter lead and stayed there.

"All of a sudden I realized, 'He's not advancing anymore. He used all his energy to get up to me,'" Nunn said. "At that point, my legs started coming back and I thought, 'Let's just get up to him.'"

Nunn reeled in Seeman and the two Olympians walked side by side through 48 kilometers, setting the finish for Nunn's plan.

"I decided with 1 ½ kilometers left, I would take off," Nunn said. "I wouldn't just start pulling away. I was going to drop it. And he was going to have to make a quick decision whether he wanted to try to fight to hang with me or just let me go."

When Nunn dropped the hammer, Seaman had nothing in the reserve tank. Nunn walked his last kilometer in 4:18 -- faster than he usually finishes a 20K race -- for a 1:09 margin of victory.

At the awards banquet Sunday night, Nunn told the audience, "For the first time in my life, I became a true fan of race walking today. I had a front-row seat for one of the most exciting races that has happened in decades for race walking."

"With three laps to go, Tim and I were walking virtually shoulder to shoulder," Nunn said. "And every time we came around, that crowd was going nuts. We were going back and forth for the lead. In my mind, I knew how it was going to end, but at one point I put myself in a spectator's viewpoint and I remember thinking with three laps to go, 'This is awesome.' It felt like it was 12 rounds of a heavyweight boxing match."

Later that evening, Nunn checked in with the reactions of both athletes' fans on Facebook.

"I don't think there's been that much talk about race walking in America in a long, long time," he said. "It was an unreal race for the last 30 minutes. I've never seen anything like that before in my life. It was a fun time."

Nunn commended Seaman for his effort, and applauded the Army and his coach for sticking with him in times that were not fun.

"If people had been out seeing what coach and I have been doing over the past six months, I think they would be shocked with the amount of work because it wasn't just the training," said Nunn, who is coached by Enrique Pena. "He is the most positive guy I have ever been around. I was in tears a little bit when they were interviewing me yesterday.

"It's been a long road, and a long road back, and it's great to finally be back," Nunn continued. "Throughout that time, life goes on and everyone has adverse situations, but there were times when I went through my divorce where I would just quit the workout. I would sit down and couldn't stop thinking about it, and coach would just look at me and say, 'John, that's OK. Go home, and let's try again tomorrow.' And when I was fat -- at my heaviest I was 210 -- coach would say, 'You can get the 'A,' you can get the 'A.' C'mon, let's focus on the 'B' for now.'"

Others believed what Nunn could not fathom.

"There is no question in my mind I would not have made the 2012 Olympic Team without the Army putting the pressure they did on me," he said. "I thought at the time, and part of me probably still thinks, some of the benchmarks they asked me to hit were pretty outlandish, pretty far-fetched, compared to what other track and field athletes were being asked to do."

Nunn would hit one benchmark, and then get tasked with another he thought unattainable.

"I thought, 'Well, this has been fun. I guess they're going to release me.' Then I thought, 'Why don't you do what's right, put your priorities in order, and see what you can pull off?'"

Nunn drastically changed his diet and lost 30 pounds during the next three months. He turned to weights for strength training beyond running. He got more sleep.

"I made it my life," said Nunn, who began writing things on his mirror as a daily reminder of what it would take to get to London.

For the past two months, the mirror read: 4:05.

His winning time Sunday was 4:04:41.

Nunn's 7-year-old daughter, Ella, even got into the act by climbing on his dresser and painting Olympic rings on the mirror with a magic marker.

Nunn is eager to take Ella to London. She accompanied him to Athens, but has no memory of that trip. Nunn did not make the U.S. Olympic team for the 2008 Games in Beijing.

"We have pictures up all over the house of Ella when she was a little baby in Athens, and we've talked a lot about it," said Nunn, who has Olympic rings tattooed on his back. "Anytime anybody asks anything about it in school, Ella will raise her hand and say, 'My dad is an Olympian.' She knows about it, but she was six months old when we went to Athens and she doesn't remember anything."

Nunn knew little about race walking when he finished 26th in the 20-kilometer race walk at the 2004 Olympics in Athens.

"I think, quite honestly, in '04 I didn't know what I was doing," Nunn said. "I went off of athletic talent and ability and I made the team. I remember it took me a couple years even after going to Athens, to be like, 'Wow, I'm really an Olympic athlete.' And when my training and things went bad, I felt it was a fluke.

"This is the first time in my life I have put everything in order and prioritized. And along with that, you can't forget that being a single dad, I have massive priorities with Ella, too. I don't go out a lot. I got to bed at 8 o'clock or 8:30. There are a lot of things that play into it. I've only gotten in the best shape of my life during this past year.

"I made a very mentally concerted effort of focusing what I needed to do to get to where I wanted to be, so this one is very special."

Another WCAP benchmark popped up Sunday: Nunn needed to hit the "A" standard or win the race and hit the "B" standard. He did the latter.

"Why?" Nunn hypothetically asked. "Because you have to -- there is no other option anymore. This is what's going to happen. The Army putting the benchmarks forces me to think that way. Maybe I'm starting to learn to thrive on pressure."