The ultra-runner, who was experienced but unfamiliar with the trail she had taken with her brother-in-law in California's Cleveland National Forest, was severely dehydrated and nearing kidney failure.
And, then, on Wednesday, she saw the helicopters flying overhead. Although described as "beat up pretty good" by a rescue worker, the Californian was able to attract their attention.
"I'm doing great," Natera-Armenta, 36, told "Good Morning America" today from her wheelchair in the hospital. "I'm so happy to be alive."
Natera-Armenta had set out on the park's Hot Springs trail around 7 a.m. Sunday with her running partner and brother-in-law, Fidel Diaz, 53. The two regularly compete in races of 50 to 100 miles but were accidentally separated a few hours into their planned 25-mile run.
When the trail ran out and the two tried to get across a creek to more manageable terrain, they lost each other. Not carrying a cell phone because there is no reception in the area, Natera-Armenta began trying to find her way.
"I can think it was probably about eight hours, or so when I realized I had to stay there and I had to remain calm and rest and wait for the next day," she said.
Natera-Armenta then dropped one of her precious water bottles in a ravine. Lost and low on water, she decided to stay put. She took shelter in the shade of a boulder, in a steep, sloped area thick with dry brush.
Natera-Armenta's husband, Armando Armenta, said he was used to his wife's long runs and that when she didn't come home Sunday, he assumed she was staying with family in the area, as she often does.
"When I came home Monday, and I realized she still wasn't home, I just realized something wasn't right," he said.
Diaz, himself missing for several days, made it out of the forest on his own Wednesday morning. He was immediately questioned, some people wondering if he was involved in his running partner's disappearance.
But Natera-Armenta's husband said he never believed that.
"I was just glad to see him. I was glad that he was OK," Armenta said. "Seeing him gave me hope that I was eventually going to see Gina alive."
Teams of sympathetic ultra-runners, along with local authorities, combed the trails looking for her.
Natera-Armenta said that she began to get ill -- and worried.
"I was having stomach issues, and I had been seeing helicopters in front of me, behind me, to the right of me, but never near where they could see me," she said. "And that's when I began thinking they were not going to find me."
Although worried she might not make it, Natera-Armenta said, she kept her focus by trying to remain calm and thinking of her family. There was a waterfall nearby, but she could not reach it.
"I knew the only way they would find me alive was definitely by saving energy," she said.
Finally, at 1:30 Wednesday afternoon, Natera-Armenta heard the sounds of a police helicopter overhead.
"She came out waving, we saw her at that time," said Tim Perkins of the Mission Viejo Fire Department. "She looked like she had been out there for a while. She didn't have any shoes on, she looked like she was beat up pretty good."
Now Natera-Armenta is focused on her recovery, which includes lots of fluids and rest.
When asked if she still held a passion for running, she smiled, saying, "Of course, I do."