Ryan Shazier has officially announced his retirement from the NFL.

"When I was 5 years old, I made the greatest discovery of my life," Shazier said in a video posted to Twitter on Wednesday. "I discovered the game that I love -- the game of football. Ever since then, I've given my life to the game. I love everything about it ...

"Football gave me everything I ever wanted and more. It taught me about hard work, dedication, teamwork. It took me to college and the NFL. It made me money and gave me a life most people could only dream about. I'm here today to make sure the world knows how much I still love football, how grateful I am for everything football gave me. And I'm here to let the world know that today, I am officially retiring from the game I love so much."

Shazier was rushed to a University of Cincinnati hospital on Dec. 4, 2017, after a tackling attempt against the Cincinnati Bengals on Monday Night Football left him struggling to move.

Shazier underwent spinal stabilization surgery a few days after, and he didn't regain movement in his legs until the following February.

"To lose the game in a way I never envisioned has not been easy," Shazier said in his video. "When you play the game of football the way I did, you convince yourself you're Superman. That nothing can stop you, but then the moment I got hurt, I stopped being Superman. That was difficult to make sense."