Of course, you've heard about all the long-term risks associated with playing professional football.
Furthermore, the sport used to be much more hazardous than it is now,in 1905, 18 players died, the majority of whom were high school students.
Yet only one player has perished on the field in the NFL's history.
On October 24, 1971, Chuck Hughes of the Detroit Lions passed away at the age of 28.
Hughes sat on the sidelines for the first three quarters of their contest with the Chicago Bears.
Hughes entered the game to replace a (not seriously injured) player with 10 minutes remaining. He caught a pass with two minutes left to play. Then, with 62 seconds remaining, he passed out.
Some Bears players began yelling and swearing at Hughes because they believed he was fabricating an injury to get an extra timeout, as they later admitted.
Hughes wasn't lying. He was taken off the field on a stretcher after a team of doctors tried CPR on him. The hospital's medical staff would keep trying to revive him, but he was already dead.
Despite Hughes death, play resumed because Nothing in the rules mandated that you end a game early when a player passes away.