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Mental health and the mental toughness it takes to succeed in professional sports took center stage during Tuesday's star-studded episode of HBO's The Shop.

Former New England Patriots tight end Rob Gronkowski, Cleveland Cavaliers forward Kevin Love and Portland Trail Blazers guard CJ McCollum joined a list of celebrities that included Kevin Hart, Lil Nas X, Maverick Carter and Charlamagne Tha God and opened up about a number of topics.

Gronkowski surprised some when he walked away from the NFL after last season's Super Bowl win, but he painted a picture of the demanding nature of playing on the Patriots.

"You're not treated like a super-super star in that organization," he said. "Not even Brady."

The future Hall of Famer also explained it is seen as mental toughness in the NFL to fight through injuries and still take the field even when not feeling well, which was even harder for him given his lifestyle away from the sport.

"I felt like I had to get away from the game and focus on my health," he said (warning NSFW):

It was clear playing football took a toll on Gronkowski from more than just a physical aspect, which is notable after he told Ian Rapoport of NFL Network on the RapSheet and Friends podcast that he "could easily go out there right now and go" because he still has plenty of game left in the tank.

Few people are in a better position to understand the mental health aspect of being a professional athlete that Gronkowski talked about than Love.

He opened up about his anxiety during a 2018 interview with the Today Show and in an article for the Players' Tribune. He revealed he had a panic attack during a game against the Atlanta Hawks in the article and stressed during Tuesday's show how important it was for him to write it because he didn't want anyone else telling his story.

"I was afraid to be myself," he said of his early days on the Cavaliers as he transitioned from being the star on the Minnesota Timberwolves to a secondary option alongside LeBron James and Kyrie Irving. "It's not a quick learning curve taking a back seat."

While mental health was the primary topic, Love and Gronkowski also talked about the positive impact of their fathers and how that helped pave the way for their athletic careers.

Lil Nas X also discussed his sexuality as a gay man, and McCollum and Love both agreed the stigma in professional sports is a major reason more athletes have not come out.

The show circled back to mental health and its relationship to performance when it concluded with a conversation about what it takes to be among the greatest of all time.

James and Tom Brady both came up as former teammates of Love and Gronkowski, respectively, and the consensus was they reached their level of greatness based on more than just physical genes (warning NSFW):

Few people in sports history could lock in as well as James and Brady, and the results have been numerous championships and individual accolades.

Gronkowski and Love know that better than most.