He’s a tough guy but it took a talking tree monster to help him deal with the death of his best friend.

Vin Diesel opened up about his grief over the loss of Fast & Furious co-star Paul Walker in a tragic car accident on November 30, in a Q&A session on Facebook promoting Guardians Of The Galaxy.

The muscleman credited Groot, the tree monster he voiced in the Marvel film, for helping him get back to work.

Muscle man: Vin Diesel, pictured in Los Angeles on Wednesday, has revealed how playing Groot in Guardians Of The Galaxy helped him cope with the grief of Fast & Furious pal Paul Walker’s death on November 30

Vin’s own personal guardian: Vin Diesel lent his voice to the character of Groot, a tree monster, in Guardians Of The Galaxy, saying he found the experience ‘therapeutic’ after Paul’s death

The character can only say, ‘I am Groot,’ and Vin had to use the phrase in dozens of different ways to express what the character was feeling.

Answering a fan’s question on Monday, Vin wrote: ‘It was the month after the accident happened with my brother Paul Walker and it was the first time I had worked since.

‘Although it was challenging, just to get back to work was therapeutic — especially as Groot. There was an innocence about the character that was just refreshing — and it may have been more challenging under other circumstances, but at that time, it was very therapeutic.’

Reaching out: The actor, dressed in a revealing white vest and black trousers, flexed his considerable muscles as he opened his car’s rear door

Chilling out: The hunky star stopped for an iced coffee during his trip to an eyewear store

The gig came after work on Fast & Furious 7 stopped following Paul’s death when the limited-edition Porsche he was riding in, driven by his friend Roger Rodas, crashed at 3:30 pm in Valencia, California. A coroner has concluded that both deaths were an accident.

Director James Wan and the movie’s producers had to decide whether to finish the film or not. They opted to continue, using the actor’s brothers and computer-generated images of his face to create his likeness.

The crew were filming in Malibu earlier this week, and Vin took time out to do some shopping at an eyewear store in Los Angeles on Wednesday.

Suited up: Paul Walker, Vin and Tyrese Gibson at the Fast & Furious 6 film premiere in London last May

The celebrity showed off his bulging muscles in a white vest, black trousers and heavy black shoes as he made his way back to his car.

He wore a large silver cross on a long chain around his neck and threw a black bag over his shoulder, as he carried a cup of iced coffee.

Car caper: Paul and Vin in a typical pose from the fifth movie in the blackbuster franchise, Fast Five, in 2011