Cena gets to grips with Hollywood

"I just started telling directors, 'Hey don't be afraid to tell me to turn it down. You're going to have to do that because of the world I come from,'" he said. "Tell me I suck and tell me what you need."

It's not uncommon, he said, for a director to come from behind the monitor and say, "You're at a 10, I need you to be at a 1."

"I'm humble and vulnerable enough to say I'm still learning," Cena said.

One person he's learned a lot from is Jackie Chan, who he is co-starring with in a 2019 action film from Scott Waugh.

"I firmly believe he's a robot because he does not know the word stop," Cena said.

For now, he's still happy juggling both the WWE and his rising film career, and every time he has a spare minute, he's either looking for another acting project or looking for a WWE engagement.

He was supposed to have a month off after Bumblebee came out before his next film starts shooting, but he decided to find out what WWE events are happening instead. Now, he'll be doing that right up until he has to leave for the film.

"None of those are televised," he said. "I just want to go back because I love it. When that process becomes too much, I'll be at the precipice of a choice. But it's not right now and I'm enjoying it."