Arnold Schwarzenegger is reflecting on a particularly challenging time in his life when he had unplanned open heart surgery and had only a matter of months to recover and be back to top form.

In a video posted recently to his YouTube channel as part of his health and fitness group, Arnold's Pump Club, the 76-year-old actor and bodybuilder recalled a frightening incident in early 2018 when he was supposed to undergo non-invasive heart surgery.

"I remember when I had my open heart surgery, my third one... I was really freaking out, and I woke up all of the sudden and the doctor was standing in front of me, and saying 'I'm so sorry, but unlike what we planned, a non-invasive surgery... we made a mistake and poked through the heart wall, and there was internal bleeding, and we had to open you up to save your life.'" Schwarzenegger recalled.  

"The bottom line is, you cannot roll the clock back," he continued. "I was in the middle of a disaster... so now it's about, 'how do I get out of it?' You have to shift gears."

Schwarzenegger said he realized that the first step to recovery was getting healthy enough to get discharged from the hospital.

"[That meant] getting out of bed and start walking. First 10 steps, then longer and longer," he explained, adding that when he needed extra motivation, "I called my buddies in and said, 'You guys have to fire me up. You have to count the number of steps that I'm doing.'"

"And this is what we did, everyday. Everybody came into the hospital, They said, 'OK, Arnold, it's time to get up!'" Schwarzenegger recalled. "I wanted to get really going with the exercise, get out of the hospital as quick as possible, and then get going with the training again."

"Because three months later, I started with Terminator 6," he said, referring to Terminator: Dark Fate, which was set to start shooting after multiple delays. "So I had to be in shape, I had to be able to move around, run around, lift things up, do the fight scene, all these things."

As Schwarzenegger reflected on his recovery journey, he also shared behind-the-scenes footage, both of him in the hospital and then training on workout machines after getting out.

"And I did it! Because I had a positive attitude and knew exactly how I was going to get there," he explained. "[And] I had the support system, because none of this we can do by ourselves... When I started shooting Terminator 6, I was all back together again."