Former Michigan starting center Jack Miller announced earlier this month he would not play his senior season and on Wednesday he told ESPN concern about the long-term impact from past and possible future concussions was a factor in the decision.
"I know I've had a few and it's nice walking away before things could've gotten worse," Miller said. "And yes, multiple schools have reached out. But I'm ready to walk away from it. My health and happiness is more important than a game."
Miller is focused on finishing his degree and pursuing business opportunities. Miller said he had one concussion in high school and "probably" two or three at Michigan, though he said he reported only one.
"I wanted to keep playing," Miller said. "You're supposed to be tough in this game, everyone carries that attitude."
Miller played in 22 games at Michigan. He started 16 times, including all of the 2014 season, when he won the team's award for best lineman of the year.
"I know it's pretty unorthodox for a 21-year-old to see past his own nose," he said. "This game requires such a passion to excel, and my flame is burned out.
"However, I'd be lying if I said that the concussion thing doesn't scare me a little."
Miller said he isn't sure if he would allow a future son to play the game.
"Football has taught me so much about life, it's incredible how much I've learned from it. That's why my dad ultimately wanted me to play the game at a young age, then we found out I was good," he said. "But is it worth the potential injury? Really tough call."
Miller's brother Matt was a highly-recruited Wisconsin offensive lineman who retired after freshmen preseason workouts due to the effects of multiple concussions suffered in high school.
The Big Ten has announced an independent athletic trainer will be stationed in the video replay booth in the 2015 season to look for players who show visible signs of a concussion.
The move came after Michigan was criticized for its handling of a head injury sustained by quarterback Shane Morris in September.
Morris, whose center was Miller, was allowed to play after taking a late hit that left him wobbly.
"It's a good gesture," Miller said, adding he likes a new NFL policy that will allow for a medical timeout to be called if a player appears shaken or disoriented.