Birthday Biceps: Checkout How Dwayne Johnson Is Celebrated His Birthday (Photos)

He's known as one of the hardest working men in the entertainment industry.
And on Friday Dwayne 'The Rock' Johnson showed why, as he celebrated his 42nd birthday in typically intense style.
The actor hit the gym for a early morning arm workout and then hit the set of San Andreas, a film he's shooting in Queensland, for some birthday stuntwork - all of which he documented for fans on Instagram.
Honouring great American boxer Muhammad Ali, from whom The Rock took the 'People's Champion' moniker in his wrestling days, the bulked-up actor wore a Cassius Clay jersey for his workout.
Pumping some seriously heavy iron, The Rock focused on his arms for the workout, seen on Instagram doing some ferocious bicep curls.
'Appreciate my own gym playin' Happy Birthday by Stevie Wonder as I walked in,' he said on Twitter, before hashtagging 'AussieLove'.
He then went to the set of San Andreas, where he shot a 'massive action scene', uploading a video of himself para-sailing down a cliff.
The film, though shot in Australia, is based in California following an earthquake, which is why The Rock was seen wearing a Los Angeles Fire Department uniform.
The former professional wrestler was recently enjoying the sights of Australia, taking a snap of himself riding a jetski about the Sunshine State's picturesque waters.
He's been Down Under since mid-April, and started filming San Andreas last week - the film is due out in 2015.
The Rock will next star in the historical action blockbuster Hercules, hitting cinemas worldwide later this year.
This all follows a landmark year for the actor, as between Fast & Furious 6, Pain & Gain, G.I. Joe: Retaliation and Snitch, he became 2013's highest grossing Hollywood performer, with a combined total of $1.3billion in box office receipts.