"Thoughts went through my head: 'I could die out there,' just for the simple fact that I didn't know what the problem was," Exum told the St. Paul Pioneer Press in an email. "But I knew we didn't have anyone else [to play] safety."
Exum suffered a fractured rib and an injured AC joint in his shoulder trying to tackle Seattle Seahawks tight end Luke Willson in the first quarter of a game Dec. 6. However, because the Vikings were short-handed at the position, he chose to keep playing even though he wasn't able to run at full speed with the injuries.
"I was feeling a pain in my chest with every breath and motion," Exum wrote to the Pioneer Press. "It was scary because I didn't know what it was."
He was placed on injured reserve two days after the game.
"I knew that the way I compete sticks to a code of never giving up," Exum wrote to the Pioneer Press. "I knew that it means a lot to the guys next to me. Therefore, I couldn't come out.
"I know I didn't play my best game, and that hurts me because I left it all on the field from an effort standpoint and we came up short. But I'm a warrior and made a choice to keep playing when I thought my life could have possibly been on the line. That, I can live with."
ESPN Staff Writer Ben Goessling contributed to this report.