Boxing movies have given actors the opportunity to get into ridiculous shape for decades.

But the "Rocky" franchise brought it up another level. The physiques of Carl Weathers as Apollo Creed and Sylvester Stallone as Rocky Balboa (who by the third film looks ridiculously cut) was the inspiration for many during the exercise craze in the late 1970s to early '80s.

Now the bar has been raised once more with the "Rocky" spin-off film, "Creed."

Michael B. Jordan plays Adonis Creed, the illegitimate son of Apollo who with the help of Rocky as his manager pursues a career as a professional boxer.

To get the look of a pro boxer, Jordan called on personal trainer Corey Calliet. The two had first met on the set of "Fantastic Four" and hit it off.

"I remember on set of 'Fantastic Four' there was talk of Mike doing 'Creed,'" Calliet told Business Insider. "I grew up watching 'Rocky,' and they were so ripped, but I knew with my skills I could do better."

So even before "Fantastic Four" wrapped Calliet began a regimen with Jordan, who played Johnny Storm in the movie, that made him into, as Calliet calls it, "an action figure."

"I remember Hutch [Parker], one of the producers on 'Fantastic Four,' called me and said, 'Corey, you're doing a great job but tone it down a little bit because Michael can't fit in the suit,'" Calliet said.

Once filming wrapped on "Fantastic Four," Jordan brought Calliet out to Los Angeles, where they continued to train and meet "Creed" director Ryan Coogler, who immediately agreed to have Calliet be Jordan's trainer on the film.

Brothers from different Mothers!! #greatnight #fightnight #michaelbjordan #vegas 💯💯 A photo posted by Corey Calliet➡️mis•ter kai-yay (@mrcalliet) on Nov 22, 2015 at 1:21am PST Nov 22, 2015 at 1:21am PST

By November 2014, Jordan and Calliet began training in Philadelphia, where filming would take place. Filming began in January of this year, and training continued. But by that point Calliet did different workouts depending on the scenes they were shooting.

"Ryan told me how Mike needed to look for certain scenes, so I would feed him creatine types of food so his muscles would pop on a specific day," Calliet said.

And Stallone took notice.

"Sly has said he thinks Mike is in better condition than he was in for the 'Rocky' movies," Calliet said. "That is very big for me."

Here's just a glimpse of the workout Jordan did six days a week:

— 45 to 60 minutes of cardio

— Three sets of 25 reps of sit-ups every other day

— One-mile warm-up on the treadmill

— Two sets of 10 reps of push-ups

— Four sets of dumbbell curls

— Three rounds of 20 reps of box jumps, jump squats, and burpees

— Boxing training (heavy bag, speed bag, jump rope)

See Calliet's complete workout regimen at Men's Journal

"I remember when we started out Mike couldn't lift 25 pounds, but then I started to see the confidence as he could see results," Calliet said. "Now he jumps rope better than I ever could, and I fought Golden Gloves."

But Calliet said Jordan hadn't even hit his potential. Like Rocky managing Adonis, there's still more Calliet can show Jordan, and he hopes a "Creed" sequel will give him that opportunity.

"I promise you he's going to be bigger and more cut," Calliet said when asked about a sequel. "And if he becomes a heavyweight for the next movie? Oh my god, I've got a trick for ya'll."

"Creed" is now playing in theaters nationwide.