Chef Robert Irvine stays jacked at 58 by working out every day, even if he has to hit the gym at 3 a.m.

• The celebrity chef and Royal Navy veteran Robert Irvine hits the gym daily, even while traveling.
• He sometimes works out in the middle of the night, fitting in exercise no matter the time zone.

Robert Irvine doesn't believe in rest days.

Not in his career as a celebrity chef and the star of multiple hit Food Network shows, which involves 345 days a year of travel worldwide. And certainly not in the gym, where the trim, muscular 58-year-old can be found exercising at all hours, day or night.

"I don't take days off," Irvine told Business Insider. "Health and fitness has been a staple since I was 11 years old."

A veteran of the British Royal Navy, Irvine says his routines combine classic strength exercise with training for real-life durability, allowing him to tackle feats such as marching more than 50 miles across Scotland to raise awareness and resources for military charities, a focus of his Robert Irvine Foundation.

He has, however, adjusted somewhat over the decades, at least to incorporate daily stretching and easing off all-out maximum lifts to prevent injury.

"I am doing a slightly different routine at 58," he said.

Irvine shared how he fits in workouts in a hectic travel schedule, what he does in the gym, and how he's training to stay strong for years to come.

He follows a strict schedule for gym time

Irvine says the secret to his consistency in the gym is simple discipline — making the time to fit in a workout seven days a week, regardless of the time zone.

"No matter where I am, I do an hour-and-a-half workout, even if it's midnight or three in the morning local time," he said.

Generally, rest days are advisable. Irvine's trainer encourages him to take a least one rest day a week, according to a person on his public-relations team — but Irvine says time spent on a plane during his worldwide travel counts as rest, so he's ready to hit the gym when his flight lands. While it may seem grueling, he says keeping to his usual timing helps him stay on track despite being constantly on the move.

"That's how I'm wired," he said. "I stay in the time zone I'm used to living in; I don't change my routine for that."

His workouts target a different muscle group each day

Irvine follows a traditional body-part workout split in the gym, dedicating a separate day of the week each to shoulders, legs, arms, back, chest, cardio, and abs. The final day is dedicated to light cardio for some active recovery.

The routine reflects his longtime interest in classic bodybuilding, focused on packing on muscle.

"I'm old school," Irvine said. "When you're young, you want to be Arnold Schwarzenegger; you want to be big, bulky, and buff."

Over the years, however, he's incorporated a different approach to weightlifting, alternating heavier days with lighter days.

"As we get older and start to get injured based on lifting heavy weights, so you start to ease off," Irvine said. "I don't need to be lifting 570 pounds on a leg press at 58 years old so I can, what, break my knees?"

He started stretching to boost longevity and avoid injury

You may not expect someone of Irvine's stature to do yoga. And you'd be right — he says it isn't for him, and he finds pilates tough.

But after decades of pumping iron, he says a gentler approach has finally crept into his workouts in recent years. Now, each workout includes 30 minutes of mobility exercises before and after, with band-assisted stretching, foam rolling, floor work, and joint rotations.

"For 50 years, I never stretched a day in my life," Irvine said. "If I don't do this, I know I'm going to have problems with my hips."