Brock Lesnar isn't a novelty.

Despite what his resumé might convey during his time as a mean-mugging heavyweight with the World Wrestling Federation, Lesnar's foray into mixed martial arts is sincere - and resolute.

When he followed a loss to Frank Mir in his UFC heavyweight debut with a win over Heath Herring (UFC 87, August 2008) and a second-round TKO of Randy Couture, an MMA legend with his own action figure, people noticed.

After that Couture fight at UFC 91, which made Lesnar a champion, his enviable size and increased skills every time he stepped in the Octagon were noticeable - and somewhat frightening.

It just didn't make sense.

It didn't compute that this behemoth who once wore a black Speedo while bodyslamming other dudes wearing Speedos could make the switch to MMA, a sport that takes more than brawn, a fake tan and GNC-bought muscles to be a champion.

Lesnar, 34, was a natural. An enigma. A breath of fresh air in the sweeter science of today's mixed martial artists. Because Lesnar got in there and used his 6-3, 265-pound, corn-fed frame to beat the stuffing out of whomever UFC boss Dana White paired him with. In his life, he's had brief stints as an actor, a professional wrestler and was even in an NFL camp with the Minnesota Vikings (2004), but it was quickly apparent that perhaps the life of an MMA fighter was his true calling.

He rose quickly to the rank of heavyweight champion, a title he fought to defend three times, winning twice and losing to Cain Velasquez in UFC 121 in October 2010. His battle against fellow heavyweight Shane Carwin became the quickest rivalry in UFC history, and his second-round win in a bloodbath to become UFC's undisputed heavyweight champ against Mir in UFC 100 is replayed to this day on highlight videos. It also served as revenge, considering Mir spoiled Lesnar's debut with a submission in Round 1 (UFC 81, February 2008).

But they say time brings all good things to an end. In Lesnar's case, it was time - and a serious infection.

Diverticulitis.

Rearing its head in 2009 and again earlier this year, the intestinal illness cost Lesnar everything he's worked for in MMA: his title, to Velasquez, the current UFC champ; his top-contender ranking; and the bravado that made him the most feared heavyweight in the sport.

But with months of rehab and training since his last bout and then surgery, Lesnar is ready to reclaim fame and, he hopes, an eventual return to the top.

On Friday, Lesnar begins his road to redemption in the main event against Alistair Overeem - an MMA star (35-11-1), but a UFC newbie - at UFC 141 from the MGM Arena in Las Vegas.

"I've had plenty of time to train and, being healthy once again, I am motivated," Lesnar said in a recent teleconference. "I've been able to work on different things. This is a sport that you have to evolve in and you have to get better if you plan to stay on top in this organization."

In Overeem, Lesnar (5-2 UFC, 6-2 MMA) isn't getting a cookie-cutter return to the Octagon, he's getting a stone-cold killer who made a name for himself while with Strikeforce, quickly becoming the premier heavyweight in the outfit and catching the attention of UFC boss White.

Overeem has repeatedly said his battle against Lesnar won't go the distance.

"I'm prepared for five rounds . . . but looking at myself and the type of fighter I am, and looking at Brock and the type of fighter he is, looking at both our characters, we're aggressive," Overeem said. "We're fighters who want to finish fights and, yes, I am going to be doing that on Dec. 30. I expect him to be doing that, so I don't

really see [this fight] going past the first or second round. The second round maximum."

Words like that have made Lesnar a recluse. He has taken refuge at his ranch/fight farm in Minnesota, keeping away from all media as part of his training regimen. He's reverted to Twitter on occasion to provide fans updates and market his DeathClutch clothing brand. Known as @DCBROCKLESNAR, on his last posting on the site was a retweet from clothing website MMA overload that read, "RT @mmaoverload Who's ready to see Brock Lesnar back in the octagon at UFC 141?? . . . "

Perhaps no one more than Lesnar himself.

"Put lots of hours in the Octagon in training," Lesnar said. "Lots of sparring, lots of grappling and lots of jiujitsu sessions. It hasn't been for a lack of trying here. I am excited for this [opportunity] and I can't wait to get back into the Octagon. I am not going to make statements, but I am going to try and do my best to win this fight and that's really all I can control."

Time. It's the most precious resource we have been granted on Earth and the one that most of us can make with it what we choose. Brock Lesnar chose to train his body to beat an infection that nearly killed him and beat in the faces of anyone who comes between him and his quest to, yet again, become one of the most vicious fighters in the MMA game.

Judging by his history, it appears he has made the right call.