Curtis Sims, a service manager at Great Plains Kubota, a tractor dealer in Duncan, Oklahoma, first tested positive on Oct. 19, but it wasn't until Halloween that he started to feel the effects of COVID-19, he told ABC News.

Sims initially thought he was dealing with a chest cold, telling his boss that he expected to be back to work in a couple of days after the quarantine period was through. But the symptoms worsened dramatically and Sims said it was hard to breathe.

When Sims' wife, Suzanne Sims, dropped him off at Comanche County Memorial Hospital that day, he figured he would be going home later that day. But his condition continued to deteriorate. The last thing he remembered was a nurse who sat with him that night as he underwent sedation.

Sims remained under a medically-induced coma until late December 2020. He was placed on a ventilator on Nov. 15, 2020.

Lacey Anderson, an ICU nurse at Comanche County Memorial Hospital, told ABC News that when she first saw Sims his entire body was swollen -- likely due to his kidney or other organs not functioning properly and therefore not able to flush out the fluids and other medications being administered to them, she said.

Anderson, who cared for Sims for three days, was not sure he would make it through his treatment. On the fourth day, he was airlifted from the small hospital to the University of Oklahoma Medical Center in Oklahoma City.

Anderson was distressed that she could not offer Sims' wife any good news when she came to see him that day.

"I just kept thinking...'Please, God, let him make it through this. Let him be able to get on that flight to get to OU today," she said.

While at OU, Sims' family was called into the hospital to potentially say goodbye. Sims had specified on his "Do Not Resuscitate" order to only revive him twice, and he had already coded as many times, he said.

When Sims woke up, "everything was foggy," he said. It was difficult to remain calm and to push enough air out to talk. He did not have his phone or his glasses. When the medical staff asked him questions, he answered as best he could.

"I was basically just guessing and hoping that I would get better," he said.

It was not until several days later, as he came to, that he started to ask questions. He did not realize how much time had gone by -- that he missed his birthday, Thanksgiving, Christmas and his father's funeral. He did not know he was in Oklahoma City.

"When you wake up and you've missed that much time, it's hard to go back," he said. "I mean, you just can't. You don't know how to fill in those pieces in your day...in your mind. It's just all blank."

Sims started feeling better around mid-January and was discharged on Jan. 28 2021  to a rehabilitation center. He required therapy, to learn how to swallow again. The first solid food he ate was lasagna, and the first thing he set his sights on when he was able to go home on Feb. 12 2021 was his recliner chair.

When Sims first visited Anderson at the Comanche County Memorial Hospital, he was unrecognizable, she said. Sims' case was a breath of fresh air among all the devastation the medical staff has faced in the past year.

"It brought tears to my eyes," she said. "I was just so excited because...we don't see that very often at all. And it was just so motivating for me."

If Sims could go back, he would change his stance on wearing a mask. He believes he contracted the virus at work, where he felt it may make customers uneasy if he were wearing one and they were not, he said. At the time, Oklahoma did not have a mask mandate in place.

"Just wear a mask," he said. "It's so simple."

He is now feeling "a whole lot better," he said. "It was some pretty dark days there for a while."