The 24-year-old actor was diagnosed with the condition aged three when doctors discovered he had been left with permanent brain damage after not being able to breathe when he was born.
After undergoing intense occupational and speech therapy throughout his childhood, RJ took acting lessons aged 11 and at 13 was cast in U.S. TV show Breaking Bad as Walter White, Jr., the son of Bryan Cranston's chemistry teacher-turned-drug baron Walter White.
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He may have found fame thanks to his role on the hit show, which ran from 2008 to 2013, but RJ thinks his condition keeps him from being cast as the lead because his speech isn't clear enough for casting agents.
"I'm never going to be hired as a leading man," he told Britain's Daily Telegraph newspaper. "Because I don't sound like a leading man. Even if my speech doesn't sound too bad to some people, it still gets in the way. Casting agents want a leading man who sounds crisper."
Despite the symptoms of cerebral palsy, which as well as difficulty speaking include weak and stiff muscles, trembling and sensory impairment, the actor says he is not short of work
"It doesn't stop me - I am working all the time," he shrugged.
However he adds that he's scared about how the condition will impact him as he ages, saying, "I'm going to be a mean old man, because I'll be hurting, I have arthritis already."
RJ can next be seen presenting for British network Channel 4's coverage of the Paralympic Games, which begin in Rio de Janeiro, Brazil next month.
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And the star says he is full of admiration for athletes who will compete in the sporting event for those who have varying disabilities.
"These men and women are athletes, these are warriors, these are people who are not confined by what they have been given. It's amazing to see where and how far the human body can really go."
The 2016 Summer Paralympic Games begins in Rio on 7 September, 2016.
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