Brett Favre estimates he suffered 'thousands' of concussions over 20-year career

The NFL's emphasis on player safety has evolved significantly over the past few decades. 

Most of the focus has been on preventing head injuries. This season, the NFL made Guardian Caps mandatory for select positions over the first two weeks of the preseason. 

While concerns over concussions and their impact are treated seriously nowadays, that wasn't always the case. 

Hall of Fame quarterback Brett Favre estimates he suffered a number of concussions over his 20-year NFL career. 

Once ignorant of what a concussion was, Favre's perspective on how many he may have had has changed since he hung up his cleats. 

"Concussions happen all the time," Favre said, appearing on The Bubba Army radio show. "You get tackled and your head hits the turf, you see flashes of light or ringing in your ears but you're able to play - that's a concussion.

"So, based on that, [I've suffered] thousands. Had to be, because every time my head hit the turf, there was ringing or stars going, flash bulbs... but I still was able to play."