The lines between MMA and professional wrestling have been getting blurrier over the past few years. Brock Lesnar has crossed back and forth multiple times and won championships in both worlds, while trailblazer Ronda Rousey has gone from the UFC to one of the WWE's hottest acts. CM Punk was less successful going the other direction, from the WWE to a pair of ill-fated UFC fights, but the backgrounds and fighting skill sets that cross between both universes will continue to see fighters with a desire to jump from one to the other.

Enter Jake Hager, who has spent his last 13 years traveling the world as a "sports entertainer," predominantly as WWE superstar Jack Swagger. Lest you think the former WWE world champion is coming at his MMA dreams with less than an average fighter's qualifications, Hager has the type of background many fight fans wouldn't blink at for somebody coming up the ranks.

As he prepares for his debut fight at Bellator 214, as part of the undercard for the Fedor Emelianenko-Ryan Bader Heavyweight World Grand Prix finals in Los Angeles, a glance at Hager's past tells you a lot about what you can expect from him inside the cage. He attended the University of Oklahoma and began as a two-sport athlete in football and wrestling, before focusing on the latter over his final three years. As a senior, Hager set the single-season record at Oklahoma with the most pins in a single season and ultimately became an All-American.

Hager was unsure of the next step as he prepared to graduate, but even then MMA was starting to become a big part of his life.

"When I was leaving college, getting ready to graduate with a degree in finance, I had job interviews for months and months -- and nothing really was moving like a real opportunity," Hager told ESPN. "Meanwhile, a lot of my wrestling teammates at Oklahoma had started getting into MMA training. They would, you know, after the season was over they were having a lot of jiu-jitsu in the room, and even [going] as far as having striking practices in the wrestling room.

"It was definitely gaining popularity there. This is '06. This is when Iceman and Tito were making waves and really putting MMA on the map. My junior and senior year in college is when I first realized what MMA is and really started liking it," said Hager. "I went the other route -- I went into the entertainment field and started wrestling professionally, and I did that for about 11 years."

Hager was scooped up by the legendary Jim Ross and spent more than a decade plying his trade in the world of WWE. He was an ECW champion, a United States champion, won a Money in the Bank ladder match and, eventually, Hager became world champion.

Jake Hager wrestled in WWE as Jack Swagger. Miller Safrit/ESPN

There were highs and lows in his tenure there, but even as he enjoyed success and the financial windfall of a lengthy run with WWE, the possibility of competing again that MMA represented started to manifest in Hager's mind.

"Halfway through [my time in WWE], one of my college teammates, Danny Rubenstein, became a MMA manager and really started getting busy," said Hager. "I live in Tampa, Florida, and one of my other college roommates named Matt Grice was fighting for another company, and it was here in Tampa, so we got to go to the fights, my wife and I."

Hager was starting to feel the itch to jump into training and fighting as early as 2013, but his contract with the WWE and other obligations kept that from happening during that window of his career.

"Since then, we have been planning when we were going to go into it. For us it wasn't if we were going to do it, it was a matter of time because we felt like I belong in this world and that I could do very well at it," said Hager. "It was about five years of working out contract situations with the WWE and trying to fight father time at the same time, because I know I'm late to the party. Luckily for me I'm a late bloomer, so I still got a lot of growing to do."

Finally, in March 2017, Hager hammered out the details of his WWE release. He started full-time MMA training the following month, and within a few months he announced he had signed a contract with Bellator.

Over the last 20 months, Hager has been transforming his body and rounding out his wrestling skills to become a more complete fighter with an intensity that points to how seriously he's pursuing this next stage of his life and career.

"It really started when I left [WWE] and I started training with Josh Rafferty," said Hager "Of course, I'm in entertainment shape at this time. I probably couldn't even gone a two-minute round. Over a year and a half, [from] April of 2017 [to] October of '17 when we made the announcement to January 2019, it's been incredible. It's been a true body transformation. I competed at very high levels in college, [but] I'm in the best shape of my life because of it.

"It really has been a special journey. Probably one of the most incredible journeys of my life," continued Hager. "From leaving a job making hundreds of thousands of dollars to investing in yourself and having your family really sacrifice so you can go into another field and compete again professionally at the most demanding sport in the world -- it was a big jump."

Naturally there are people who question why he'd make such a leap at this stage in his life. He'll be 36 when he fights J.W. Kiser (0-1-0) on Saturday, and he had a pretty comfortable life traveling the world with WWE. The call of competition and a feeling he needed a major change of scenery were too much for Hager to ignore.

"There were a lot of questions at the beginning," Hager admitted. "Why do this? And I feel like I was very fortunate to get a lot of people around me that believed in me, and that would go on the special journey with me."

"I won't tell you that it was easy, because it wasn't. I practically have been doing two-a-days since September, Monday through Friday," said Hager.

That doesn't mean he's left the world of professional wrestling behind completely, though. He wrestled 47 matches in 2018, all over the United States as well as in Canada, England and Puerto Rico. In Lucha Underground, the narrative-heavy wrestling show on the El Rey network, Swagger (as Jake Strong) ended the fourth season as the top champion.

Between his MMA training and his weekend work inside the pro wrestling ring, Hager feels as though he has taken his career and life into his own hands -- and he's loving every minute of it.

Jack Swagger cashed in his Money in the Bank contract on Chris Jericho to win the WWE world heavyweight championship. Courtesy WWE

"Saturday and Sunday I go and wrestle professionally still on the weekends -- that's what pays the bills. There's a lot of times when I'm banging my head against a wall, I'm wondering what am I doing, [but] there's been a lot of great breakthroughs and platforms.

"It's just been so much fun to really go from a company where I didn't have a lot of control over my future to being directly in control of my future and my hard work," said Hager, "And that's been the most gratifying part about it, getting to choose who I work with.

Even as he begins his MMA career in earnest, Hager doesn't foresee stepping away from pro wrestling entirely no matter how Saturday's fight and everything beyond that point goes.

"I've been wrestling since I was 4 years old, so I have over 30 years in some form of wrestling, non-stop in my life. For me, it's who I am," said Hager. "I need to wrestle, I need to compete. I think it's a very special moment in both professional wrestling and professional MMA right now. Both are at a peak of popularity and they're not slowing down. It's only going to get bigger."

Hager's appearances in the world of pro wrestling have been an opportunity to show off the dramatic changes to his body from where he was at the end of his WWE career. He's leaner than he's been at any point since the end of his career at Oklahoma, and he's worked out a way to handle MMA and pro wrestling in a symbiotic fashion.

"When you get to go out and perform on a great pro wrestling show, it's awesome. It's hard not to enjoy it. One of the reasons why I did this is I knew becoming a Bellator professional MMA fighter would make me a better professional wrestler. And being a professional wrestler, I feel like definitely makes me a better MMA fighter. So the two hands really help each other and they complement each other, and it's a lot of hard work -- but what isn't?"

Some fight fans will scoff at Hager getting such a prominent spot, on one of Bellator's most important cards to date at a high-profile venue like The Forum in Los Angeles. In the lead-up to this fight, Hager has been adamant that this will not be a CM Punk-esque situation in which he drops in for a few fights, struggles to adapt and then walks away.

"Very exciting to be on the card. What Fedor and Bader did in the Grand Prix was so entertaining," said Hager. "But make no mistake about it -- people aren't going to like that I get to debut on this card. They're not going to like what I get paid for being on this card. But make no mistake about it -- I know I belong here, I'm going to go out there and I'm going to try to steal the show and I'm going to try to make everyone else raise their bar once they see how I fight. A lot of opportunity and a lot of excitement -- and I can't wait to prove myself."