For years, the NFL has been the most powerful entity in the American sports landscape. But recently, another three-letter acronym has the NFL worried: CTE or chronic traumatic encephalopathy. CTE has received massive amounts of publicity in recent years in connection with football and other contact sports.

Research conducted over the past decade has found evidence of CTE in the brains of former NFL players. Such evidence has resulted in a public backlash against the NFL, a $765 million settlement, and a string of notable players retiring earlier than expected. It also has a large contingent of living former NFL players expressing concern about their future health as it relates to CTE, including some of the best to ever play the game.

On the eve of his induction into the Pro Football Hall of Fame, former Denver Broncos running back Terrell Davis spoke about his fear of experiencing symptoms of CTE as he grows older, a fear he believes many former players share.

“I can’t lie, we’re all scared,” Davis said last Friday. “We’re concerned because we don’t know what the future holds. When I’m at home and I do something if I forget something I have to stop to think, ‘Is this because I’m getting older or I’m just not using my brain, or is this an effect of playing football?’ I don’t know that.”

Davis is an interesting case when it comes to CTE. For starters, he’s an unlikely Hall of Fame candidate. Davis was originally a 6th round pick and was a long shot just to make Denver’s roster at the start of his rookie year. But he soon earned a starting job and ended up being one of the best backs of his generation, despite playing just seven years in the league. During those seven years, Davis won two Super Bowls, one league MVP award, one Super Bowl MVP award, and was a three-time All-Pro.

Davis is also an interesting case because it was well-known during his career that he frequently suffered from migraine headaches. In fact, Davis famously suffered from a migraine in the second quarter of Super Bowl XXXII. With everything we know about concussions and head injuries today, Davis would not be allowed to play if his team’s medical staff knew that he was suffering from a migraine. But in the late 90’s, Davis went back into the game with a migraine.

As the story goes, Davis was inserted into the game during a goal-line situation despite telling coaches that his vision was blurred and he couldn’t see clearly. But the Broncos needed him in the game, not to carry the ball, but to serve as a decoy so that the opposing defense would think the ball was going to Davis. The plan to use Davis as a decoy on a play-action fake worked to perfection, as the Broncos scored a touchdown.

Despite missing the second quarter with a migraine, Davis went on to rush for 157 yards and three touchdowns in that Super Bowl, winning MVP and leading the Broncos to their first of back-to-back Super Bowl titles. But that game is still memorable to Davis for reasons other than the win.

“I think about that moment a lot because if they had the rules in place then, I don’t go back into that game,” Davis said last week, as he reflected on his career before his Hall of Fame induction. “And that changes a lot. Am I here, at this podium?”

For former players like Davis, it’s truly a fine line between everything football has given them and all they have because of it and the risk to their health involved in playing the game. Initial symptoms of the disease may include dizziness, headaches, and memory loss, some of which may seem innocuous or a natural bi-product of age. However, CTE can also start to impact a person’s behavior and social skills. in the later stages, speech impediments, movement disorders, and dementia are all possible symptoms, exemplifying the seriousness of the disease.

With a study published last month showing that 110 of the 111 brains of deceased former NFL players examined had signs of CTE, fear among former players is at an all-time high, and no one can blame them. Davis admits that he’s concerned and that he makes an effort to stay active to help keep his mind sharp. But surprisingly, he believes progress has been made within the game of football to make current and future generations of players safer than his generation.

“People ask me the question, ‘Would you let your kids play?’ Yeah, I would,” says Davis. “Now, 10 years ago I may have said something different. But now, the way they’re teaching kids to tackle, the fact that they identify concussions a lot faster, they sit you out a couple plays, you’re not going to practice as long. All that stuff is helping the game of football.”