He recently opened up about being bullied as a school kid, due to his scrawny appearance.

And John Cena gave a group of primary school students plenty to smile about on Wednesday during a surprise visit to Nicholson St Public School in Sydney's Balmain.

In a heartwarming video shared by Fitzy and Wippa on Facebook, the WWE wrestler surprised unsuspecting students, who were reading a book based on his new movie Ferdinand, when the Hollywood star casually entered their classroom.

Surprise! John Cena surprised a group of primary school students on Wednesday during a surprise visit to Nicholson St Public School in Sydney's Balmain

'Are you crying?' Radio host Ryan 'Fitzy' Fitzgerald asked two overwhelmed students as the group collectively gasped in amazement.

It all began with a story time session with Fitzy.

'You may have heard that [this book] is being turned into a movie,' he began.

Is it really you? In a heartwarming video shared by Fitzy and Wippa on Facebook, the WWE wrestler surprised unsuspecting students, who were reading a book based on his new movie Ferdinand when the Hollywood star casually entered their classroom

Overjoyed! Jaws dropped and the stunned students stared in amazement and laughed in excitement as he politely greeted each of them with a handshake and smile

'Now the person whose voice is being used for Ferdinand in the movie... John Cena, he is the voice of this. I don't want to read the book, is there anyone here [who'd like to read]?

Professional wrestler John then quietly entered the room before loudly interjecting: 'I'll do it!'

Jaws dropped and the stunned students stared in amazement and laughed in excitement as he politely greeted each of them with a handshake and smile.

Story time: After a few moments, the American actor began reading for the students and later held a QandA session before posing for group snaps

'Hughey and Ashton, are you crying?' Fitzy asked two students - who were visibly overcome with emotion.

After a few moments, the American actor began reading for the students and later held a QandA session before posing for group snaps.

Also this week, the star recalled being bullied for being scrawny when he was younger.

His past struggles: The star recently recalled being bullied for being scrawny when he was younger

'I was the one that was picked on,' he told The Daily Telegraph.

'I was a bit of a string bean at 11/12 years old.'

John also said he found it hard to look 'different' during that age, explaining: 'We all go through our developing stage at that age. I just didn't look like anybody else.'

Looking back: 'We all go through our developing stage at that age. I just didn't look like anybody else'

Loved up: Finding love with fellow fighter and Total Diva's star Nikki Bella, earlier in the year, John got down on one knee in front of a packed stadium at WrestleMania, the Super Bowl of wrestling

And with his past behind him, John has gone on to become of the world's most successful and internationally renowned WWE wrestlers.

Finding love with fellow fighter and Total Diva's star Nikki Bella, earlier in the year, John got down on one knee in front of a packed stadium at WrestleMania, the Super Bowl of wrestling.

And although the couple who have been dating since 2012 have plans to walk down the aisle, on Sunday, John told Stellar that kids weren't on his brain.

Happy with each other: Although the couple who have been dating since 2012 have plans to walk down the aisle, on Sunday, John told Stellar that kids weren't on his brain

'Children are wonderful. I get so much inspiration and energy from all sorts of kids around the world,' he said.

'Speak to anyone and they'll tell you two things: it's the greatest thing that will ever happen to you, and it completely changes your life. Because you are now responsible for the well being of a being, trying to figure out life.

'If I can't do that correctly, or give the amount of time needed to do that correctly, then I wouldn't want to put somebody through that,' John went on to explain.