Oklahoma tight end Grant Calcaterra is retiring from football because of multiple concussions, including a recent one in practice.

Calcaterra announced his decision Thursday in a video posted on Twitter. He hasn't played since Oct. 5 against Kansas. The junior said in the video he has had his "fair share of concussions" during his career and consulted with doctors at Oklahoma, and specialists around the country, before reaching the decision to retire.

"Football has been the biggest thrill of my life, and it kills me to know it's over," Calcaterra said in the video. "But I'm confident God does everything for a reason, and he has a plan for me. I believe football was preparing me for this moment my entire career."

To everybody who's been a part of my football journey, Thank You.



Philippians 1:6 pic.twitter.com/OmOlUsLiMV — Grant Calcaterra (@grcalcaterra) November 22, 2019

Calcaterra recorded five receptions for 79 yards this season.

He earned first-team All-Big 12 honors in 2018 after recording 26 receptions for 396 yards and six touchdowns while starting 11 games. He was an honorable mention All-Big 12 selection as a freshman in 2017. Before this season, he was fourth on Mel Kiper Jr.'s list of top non-senior tight ends for the 2020 NFL draft.

Calcaterra said he is on track to graduate from Oklahoma in May and plans to return home to California. He intends to pursue a career as a firefighter.

"I gave everything I had to this team and this game," Calcaterra said. "I'd like to think it might have caused an impact on this university, this football program and all the people around me."