Johnny Depp injured his back shooting The Lone Ranger.
The 49-year-old actor was left writhing in pain on two occasions during action scenes for the Western film - in which he plays Native American Tonto opposite Armie Hammer, who portrays the title character - and he has now realised he can't do many of his own stunts and needs to rely more on a double.
A source told America's Star magazine: "While it's been hard to accept that he can't perform such demanding feats anymore, Johnny is seeing it. He threw out his back twice while shooting the movie and then had to push through, getting massages in between takes."
As well as suffering with back pain, Depp has also been struggling with insomnia on set.
But director Gore Verbinski and the crew have been sympathetic to the sleep problems the Hollywood star - who recently announced his split from long-term partner Vanessa Paradis - has been experiencing and have adjusted shooting schedules for him.
The source added: "Johnny is also struggling with sleep problems so the crew has had to adjust to the face that he can't shoot all night. He needs at least six hours of shut eye.
"This movie has really kicked his butt. He's so happy it's wrapping up and has joked that his body wouldn't be able to take another month of it."