The ageing action man and former Governor of California hit headlines last March after he reportedly suffered complications during a catheter valve replacement operation at Los Angeles' Cedars-Sinai Medical Center, prompting doctors to perform urgent open heart surgery.
However, the star is back fighting fit and returns to screens in the latest movie in the hit science fiction franchise - which he credits for his remarkable recovery.
The actor, 72, told Britain's The Sun newspaper of the surgery: "It was kind of a surprise."
"I never get scared about these things," he insisted. "For a minute I was worried it was too close to doing Terminator 6 (Dark Fate), but I realised right away the movie is a good means to get back into shape again."
"I was home in no time and was back to the gym in no time. Most people baby themselves too much after surgery," the star added.
While Schwarzenegger had to be careful while exercising as his rib cage was being held together with wire, he was back on set within four months of the life-saving operation.
"Terminator: Dark Fate" debuts in cinemas on Friday, October 25.