JACKSONVILLE, Fla. -- Even when his symptoms worsened and he started having trouble breathing, Tony Boselli still thought he'd be treated with IV fluids and given some medicine when he arrived at a hospital here.

It wasn't until doctors told him he needed to be in the intensive care unit that he realized his condition was serious.

The former Jacksonville Jaguars left tackle ended up spending five days in Mayo Clinic while he fought COVID-19. About half of his stay was in the ICU, and he said it was shortly after he arrived there that he discovered he could be in even deeper trouble.

"It was kind of fuzzy, but I remember [the pulmonologist] saying, 'If we don't get your oxygen stabilized we're going to have to go to the next level,'" Boselli said. "I remember laying there thinking, 'What do you mean, if this doesn't work?' He says, 'We don't know what direction this is going to go.'

"I don't know if I ever was like I thought I was going to die, but I remember having the conversation with myself: I don't want to die here."

Boselli, a Pro Football Hall of Fame finalist the past four years, said his oxygen level improved enough over the next 24 hours that he didn't have to find out what that next level would have been. That was the beginning of his recovery process, and he improved enough daily that he was discharged Tuesday without needing additional oxygen at home.

Boselli, 47, said he first started feeling ill March 16, but he thought he had a cold or allergies. Then he felt much worse two days later. That's also the day he said he got a call and was told he had been around someone who had tested positive for COVID-19. He phoned his doctor and got tested that day. Two days later he received the test results that revealed he had COVID-19.

He said his symptoms worsened over the next four days, and after a rough night in which he couldn't sleep and was wheezing heavily, his doctor sent him to Mayo Clinic. His family was in self-quarantine because of his diagnosis -- he said his wife, Angie, was also diagnosed with COVID-19 but had only mild symptoms -- so the only way to communicate over the five days he was hospitalized was via text messages whenever he had the energy.

"The only people who could come in were health care workers, and they had to be in their full protective equipment," Boselli said. "They were great, though. Those doctors and PAs and nurses and techs, everyone, they're amazing. These people were absolutely amazing. Superstars."

He said he's still weak and battling fatigue, and hasn't quite shaken his cough. He still doesn't have an appetite, either -- "I had an egg for breakfast. An egg," he said jokingly -- and has lost 20 pounds over the past two weeks.

He tested negative for the virus Wednesday, and is awaiting the result of an additional test taken Thursday, but he said his doctor expects that test to be negative, too. Once he gets those results, Boselli said he's planning on getting back on his bicycle to slowly gain back his strength.

"I'm not going to be running any marathons any time soon," he said.

"It's been quite a few weeks but I'm feeling better. I'm home from the hospital and I'm on the right side of this thing now."