ENGLEWOOD, Colo. -- As a handful of media gathered around Marvin Austin, the loquacious fourth-year defensive tackle could not contain his smile. It didn't matter whether he was talking about his on-field play or the back issues that would fill at least two chapters in a medical-school textbook.

Austin is simply happy to be here. Not in the way that you don't want to hear from players in the postseason, but in a pure, ecstatic appreciation for being healthier than he has been since he broke into the NFL as a second-round pick of the New York Giants in 2011. He finally has the physical capacity to play to the potential he last showed at North Carolina nearly five years ago.

"I feel like I'm in college again. I feel like I can move around and do what they think I can do -- and what I know I can do -- as far as being able to be quick, being aggressive, bringing some swagger to the defense," Austin said.

Those thoughts were far out of his mind last November, when the back and pain issues that had dogged him since the previous year finally came to a head. By then, he was with the Dallas Cowboys, having been released by the Giants, and signed and released by the Miami Dolphins. 

In that time, his issues had multiplied. During training camp of 2012, he first detected weakness in his leg. A year earlier, he had torn his pectoral muscle and missed his rookie campaign. This was different.

"One day we were on the practice field, and I started feeling my leg tingling, and I'm like, 'What the hell is going on?' I was scared," he recalls. "I thought I was about to die or something, like I had a disease."

It wasn't like that, but it was serious. He played through it as best he could. At one point he said he could not use his right foot while driving because of the leg weakness.

Austin played on until last Nov. 3, when he was warming up for the Cowboys' game against the Minnesota Vikings.

"I couldn't stand up. It felt like I didn't have enough space in my back to stand up," Austin said. "I felt like I was going to go until it breaks. We were warming up, and next thing, I was telling (assistant) Coach (Rod) Marinelli, 'I don't know if I'm going to be able to go,' because I didn't want to hurt the team, and I definitely didn't want to get my chest rammed through and be paralyzed messing with Adrian Peterson.

"Then the doctors did an MRI, and they were like, 'No, you can't go, you need surgery,' and I just cried my eyes out, man. I knew my career was over -- being a second-round pick, being cut, and then coming back to that situation, it was over with for me in my mind."

He had a discectomy and a laminotomy, all in his lower back. Part of a disc was removed.

"The disc was probably four centimeters big, and they said it was the biggest disc they'd seen at that level and they didn't understand how I was still walking," said Austin. "So I could have been paralyzed and I played with that for two years. And then they took out some of the bone in my spine to open up my spinal canal, because I was born with a little bit of stenosis."

He passed the tests.

"I feel 10 million times better now," Austin said. "It just feels good to be able to run around, because I remember those days when I didn't have strength in my right leg, and I was taking all kinds of medicine and stuff to compensate. 

"I feel like I can be a story for anybody who has gone through adversity. Either you're going to come out punching or you lay down. And I'm a fighter."

But he first had to work back into fighting condition.

When the Broncos first called, Austin wasn't in the shape he needed to be. He was four months removed from surgery, and he couldn't work out. He had added 20 pounds to increase his mass to 340 pounds. The weight gain was from a simple source: food plus a lack of exercise while he recuperated from surgery.

"I'm a big guy, so eating was helping me cope with the situation," he said, smiling. "I started grinding and got in shape, and I came in  at around 324 (pounds)."

Three months later, Austin says he is at 319 pounds. He wants to weigh 310-312 pounds. However …

"Now, with my back, I can carry a little more weight," he said. "Before, I had to be light, because it helps take pressure off my back."

But he's still being diligent about ensuring his back can hold up under the strain. Yoga and acupuncture are regular components of his treatment, along with twice-weekly trips to a chiropractor. And these are just the beginning of the precautionary, preventive measures he takes in hoping to avoid further back issues.

"Cold tub, hot tub, every day. I'm stretching two or three times every day," he said. "I get stretched by the strength coaches. In the weight room, I don't play. I go and get it. 

"People are like, 'Are you trying to show off?' No, I'm trying to make sure that my body is strong enough to withstand what we're about to go through as far as the season. And just everything -- vitamins, I take everything, I do everything I can, because at the end of the day, I just want to be happy with whatever the outcome is, whether I'm in the NFL, whether I'm not, as long as I can say I did everything I can, I'm good."

But it's not just what Austin is doing. Strength and conditioning coach Luke Richesson and his staff help, too.

"I've been to four teams, and they way they take care of their players here is better than any organization," Austin said. "All those organizations that people think are the top in the league, they don't take care of their players like the Broncos, and that's one thing I can say with confidence, whether I'm here or not."

If he keeps playing with the performance and urgency he's maintained in training camp, he could be here a while. But he won't act like it.

"The opportunity is still there," he said, "so I'm grateful and I'm going to take it like it's my last."