Arnold Schwarzenegger is remembering a frightening moment that left him "freaking out" while recovering from open-heart surgery.

In a YouTube video posted late last month, the actor and former governor of California said that he awoke to doctors telling him that his surgery -- which was meant to be non-invasive -- turned into a much more serious procedure.

"We made a mistake," Schwarzenegger recalled the doctors saying to him in the YouTube video. This caused internal bleeding, he said, so his doctors had to "open me up very quickly to save my life."

Schwarzenegger said he was set to begin filming 2019's "Terminator: Dark Fate," the sixth installment of the "Terminator" franchise, in a few short months after the surgery, so his goal was to "shift gears" and figure out how to get out of the hospital and back on his feet.

"I was in the middle of a disaster," he said.

Getting out of the hospital meant that he had to get out of his bed and start walking, Schwarzenegger reasoned. It was a task that he enlisted his friends for, saying he called them asking to come help "fire me up" and count his steps.

"This is what we did every day," he said, adding that despite "wobbling around the hallways," the doctors told him he had to exercise his lungs because if he caught pneumonia, he could die.

Schwarzenegger made a full recovery, and gave credit to his "positive attitude" and "whole support system" for helping him get there.

"By the time I started shooting 'Terminator 6,' I was all back together again," he said in the video with a smile.

Schwarzenegger, who had a congenital heart defect, has undergone heart surgery three times.

In 2018, he had open-heart surgery to replace a pulmonary valve, following a previous pulmonary valve replacement in 1997. He also underwent heart surgery in 2020 to replace an aortic valve.