Justin Bieber has shown off his extensive tattoo work during a shirtless stint at the gymCredit: The Mega Agency

Justin whipped off his top and flexed his biceps as he walked through the gym after putting on an impressive display in the boxing ring.

His tattoo collection boasts intricate artwork depicting a crowned lion, a roaring bear and religious symbols.

Justin was joined in the gym by wife Hailey Baldwin who covered up with a long brown coat and red hooded jumper.

The singer is said to be “down and tired” at the moment – with a source telling People magazine: “He has been struggling a bit”.

Justin worked up a sweat after opening up on his marriageCredit: The Mega Agency

But pals insisted the 24-year-old’s alleged depression is not related to marital troubles with Hailey, 22.

They added: “It has nothing to do with Hailey — he is very happy being married to her.

“It’s just something else that he struggles with mentally.

“He has good help around him and is receiving some treatment.

“He seems confident he will feel better soon.”

Hailey joined her husband at the gym – but was wearing slightly more clothingCredit: The Mega Agency

A separate source told People that Bieber struggled with being in the public eye.

“He’s emotional and struggles a lot with the idea of fame — being followed, having his every move stalked by fans, cameras in his face,” the source said.

“It all sets him off and he often feels like everyone is out to get him.”

Justin Bieber let off some steam in the boxing ringCredit: The Mega Agency

Singer Justin and Hailey – daughter of actor Stephen Baldwin – tied the knot in September.

They both recently revealed they had been celibate before their marriage due to their evangelical Christian beliefs.

But earlier this month it was revealed that the couple were seeking marriage counselling – just five months after their nuptials.