Former UFC heavyweight champion Brock Lesnar revealed earlier this week that, after months of deliberating accompanied by much speculation from fans and media, he would be closing the door on MMA in favor of continuing his career as a professional wrestler with World Wrestling Entertainment (WWE).

According to Lesnar, part of the reason for his decision was that “something lacked mentally” on the MMA side of things. And Brock has always been an athlete who understands and appreciates the mental side of the game.

“Look, sporting success is a combination of effort, talent and hard work,” Lesnar said in an exclusive 2011 interview with Fighters Only magazine. “There’s got to be hard work and mental toughness, it’s not just one thing that gets you there, it’s an accumulation of many things.”

Brock became the UFC heavyweight champion when he defeated Randy Couture via second-round TKO at UFC 91 in November 2008. He successfully defended the title twice, finishing both Frank Mir (UFC 100) and Shane Carwin (UFC 116), before dropping the belt to Cain Velasquez via a TKO loss at UFC 121.

“I took a punch from Cain and he put me in a place where I didn’t know where I was and I tried to recover and he was able to keep that pressure on me,” the former champ recalled. “When the referee finished the fight I sat up and I knew where I was, but I just couldn’t defend myself. Your brain is telling your body to do things and it is not responding.”

Lesnar was originally supposed to face Carwin at UFC 106 but the fight was postponed after Brock feel seriously ill with diverticulitis – a kind of digestive disease.

“The illness was by far the worst thing,” he told FO. “That’s my health. I knew what was going on in the Octagon, but I didn’t know what was going on inside me with the illness. It was life-threatening to me.”

After losing the belt to Cain, Brock featured as a coach on season 13 of The Ultimate Fighter opposite Junior dos Santos.

“It was a good experience,” Lesnar said regarding his time on the UFC reality show. “I enjoyed it, I really did, and I learned a lot from it. It was good for me. There was something in becoming a teacher and a student at the same time. You start teaching things and you start remembering things along the way.”

As is tradition with TUF, the coaches were set to fight after the show. Lesnar vs. Dos Santos was scheduled to take place at UFC 131. Unfortunately, the same illness which had delayed Lesnar’s bout with Carwin struck for a second time and forced the TUF 13 coach to pull out.

Brock did eventually return to competition against Alistair Overeem at UFC 141. He lost the fight via TKO in the first round and announced his retirement immediately after the loss.

Now that his time competing inside the cage is done for good, we can ponder exactly what the legacy is which Lesnar has left behind as a former champion and potential Hall of Famer. He’s not one to discuss such topics too deeply, but the man himself did share with FO how he’d like to be remembered in more general terms.

When asked what he’d like to be inscribed on his headstone, Brock responded, “That’s a good one. I’d like it to say, ‘Here Lies One Tough Son of a Bitch.'”

Interview by Gareth A. Davies

For the full interview with Brock Lesnar, order your copy of Fighters Only magazine here.