Arnold Schwarzenegger's transformation in photos as he turns 79 — plus the secrets to his physique

Arnold learned from his painful injuries and admitted to Business Insider: "I sometimes trained five hours a day with weights. That's a lot of stress on the body — and clearly the body was not meant to do all that."

Now, less is more for Arnold, and he currently works out 90 minutes a day, as he remains more mindful of his body's physical limitations.

He also used to be very big on using heavy barbells, but has since adapted his workouts to smoother resistance machines instead.

He explained: "For me today, the machines are better simply because there's certain movements I can't do because of shoulder problems or knee problems."

Arnold's overall secret to longevity is to keep moving, regardless of your age or fitness level.

He revealed: "The danger is it's the beginning of death [to stop moving], because movement is life." 

The actor shared with new gym goers: "We have so many sophisticated machines now that people sometimes get into the habit of using a machine when in fact the free weights at the beginning are better."

Arnold recommends the clean and press exercise, the deadlift, and bench presses, if you're able, because they're full-body workouts.

If you need to be more mindful of your joints like Arnold, he recommends simpler workouts like rows and squats, and he shared: "The basic exercises are the most underrated exercises." Overall, any form of movement is a win for the star.

Arnold's diet has also dramatically changed over the years. During his peak body-building decades, he used to consume over 5,000 calories per day. 

Back then, his meals heavily consisted of red meat, eggs, whole milk and of course, protein shakes.

He has since switched over to a 80% plant-based diet. Now he focuses on consuming whole foods and fiber and he eats meat minimally, 

Arnold starts his mornings with four eggs and a protein shake mixed with bananas and almond milk. 

Throughout the day, he snacks on nuts and fruits and consumes lots of vegetables to stay healthy.