Rob Gronkowski has opened up on his decision to retire from the NFL and how the physical and mental impact of the game brought him to that point.

The former New England Patriots tight end, speaking at a summit advocating for players to be allowed to use CBD oil for pain, fought back tears when he said he explained his exhaustion after Super Bowl LIII.

"I want to be clear to my fans. I needed to recover. I was not in a good place. Football was bringing me down, and I didn't like it. I was losing that joy in life," Gronkowski told the crowd, in quotes published on ESPN.

Gronkowski surprised many when he retired from the NFL in March at the age of 29. He said a thigh injury he sustained during the Super Bowl against the Los Angeles Rams was what pushed him over the edge.

"I got done with the game and I could barely walk," he revealed.

"I slept five minutes that night. I couldn't even think. I was in tears in my bed after a Super Bowl victory. It didn't make that much sense to me. And then, for four weeks, I couldn't even sleep for more than 20 minutes a night. I was like, 'Damn, this sucks'. It didn't feel good," Gronkowski said.

"It was one of the biggest, deepest thigh bruises I've ever gotten."

Gronkowski also noted that the thigh bruise was so severe he had internal bleeding in his leg.

His decision to discuss the physical and mental strains of football coincides with Indianapolis Colts quarterback Andrew Luck's decision to walk away from the game at 29 for similar reasons. However, Gronkowski claimed he is happy with where he is in life.

"I truly believe going through those tough times, nine years — off the field, on the field — has brought me to this point and I believe I'm on the right path in my life," he said.

"It's a purpose to have passion in my life, to have joy in my life. And then to inspire optimal health within myself, I need to do that in order to get to a peak and then I can bring it to other people, because I know [in] the NFL, players are dealing with that kind of stuff, they're dealing with pain. I was. And I needed to walk away because I needed to do what was best for myself."

As for coming out of retirement, Gronkowski admitted he is not completely saying no, but added that mentally, he is unable to get back into the game at this point.