Brock Lesnar was serious enough about UFC return that he entered into a training camp

Brock Lesnar says that his flirtation with a UFC return was not just for leverage with WWE.

The former UFC heavyweight champion said on "Stone Cold" Steve Austin's podcast Monday (transcribed by FOX Sports) that he was so serious about making a return to the Octagon in 2015 that he actually entered into an MMA training camp late last year.

"I started training camp," Lesnar told Austin. "I wanted to test myself and see where I was -- not more physical, but mentally. I wanted to see the mental challenges that it was going to take. If your head's not in the game, the last place you want to get into is in the Octagon."

Ultimately, Lesnar was offered a boatload of money from WWE for what amounts to a part-time schedule -- no training camps required -- and re-signed with the pro-wrestling organization. But Lesnar said he thought long and hard about coming back to the UFC.

Lesnar, 38, held the UFC heavyweight title from 2008 to 2010. However, he twice missed time during that stretch with bouts of diverticulitis. Cain Velasquez took the belt from Lesnar in 2010 by first-round TKO and then Lesnar retired from MMA after a first-round TKO loss to Alistair Overeem in December 2011.

If he had been healthy, though, Lesnar said he might still be in the UFC right now.

"It was really unfair for me," Lesnar said. "To this day, I don't know if I'd be a pro wrestler if I hadn't gotten sick. I may not be here. I'd still be banging heads."

Lesnar (5-3) lost his UFC debut to Frank Mir in 2008, but then beat Heath Herring and defeated Randy Couture for the belt at UFC 91 in November 2008. Lesnar famously destroyed Mir in a rematch at UFC 100 in 2008, but he said Monday night that he wasn't really healthy after the Couture fight.

"You saw me (at 100 percent) in the fight against Randy but it got worse," Lesnar said. "When I'd get halfway through a training camp and I knew something was wrong, there's something physically wrong with me so I need to figure it out."

The former NCAA wrestling champion still ended up beating Mir and Shane Carwin after that before falling to Velasquez. Feeling like he had unfinished business with the UFC, Lesnar was interested in coming back after his WWE contract expired this past spring.

"It wasn't a bluff," Lesnar said told Austin. "I felt robbed by diverticulitis. I felt robbed by being sick. I was feeling good and it took me a couple years to start feeling good. I'm at home, I'm working out, my life is great, everything's in tune, my contract's coming to an end with WWE, hey it's been a great time but something's missing.

"I was up front and totally honest with the company and told them I'm really thinking of pursuing getting back in the Octagon."