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A U.S. Navy veteran who's broken seven world records says the key to staying strong and healthy as you age is consistency, recovery and smart training.

At 38, Mike McCastle, a performance coach from Las Vegas, recently completed one of his most demanding challenges — walking lunges for over four miles across Utah's Bonneville Salt Flats.

He set two world records in the process, but for McCastle, the meaning went far deeper.

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"Every step was a lesson for [my son] about grit, purpose and finishing what you start. Pain became information, not an enemy," McCastle told Fox News Digital.

The veteran's focus on movement and recovery comes from experience. During his time in the Navy, McCastle went through multiple knee surgeries that ended his military career.

A man in outdoor athletic gear doing a lunge exercise on a vast, flat salt plain with mountains and clouds in the distance.

McCastle is pictured lunging across Utah’s Bonneville Salt Flats, which led to him setting two world records. (SWNS)

He launched his decade-long 12 Labors Project, a series of extreme endurance challenges, to raise awareness for causes including Parkinson’s disease, veterans’ mental health and cancer, conditions that affected his late father, McCastle told SWNS.

The veteran's journey from injury to endurance taught him what builds lasting health and strength, he said. Below, he shares his top tips for staying fit and resilient at all ages.

No. 1: Start small

McCastle said the biggest mistake people make when starting a fitness journey is trying to do too much, too soon, noting that "consistency is the real engine of transformation."

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"Start where your feet are. Go for a 10- to 15-minute walk every day. Do a few push-ups. Drink more water," he recommended.

Real progress comes from stacking simple, consistent actions, according to McCastle.

Split image showing a man doing lunges outdoors and a gym dumbbell rack.

McCastle said the biggest mistake people make when starting a fitness journey is trying to do too much, too soon, noting that "consistency is the real engine of transformation." (SWNS; iStock)

No. 2: Don't skip the strength training

While both cardio and strength training are important, McCastle says building and maintaining muscle becomes especially critical with age.

"Muscle mass is protective — it improves balance, joint stability, bone density and metabolic health," he told Fox News Digital. "Cardio is great for heart and lung function, but strength training is what helps you stay independent, capable and injury-resistant as you age."

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He recommends lifting two to three days a week and walking every day.

No. 3: Make movement a lifestyle, not an event

McCastle, who trains five to six days a week, suggests building a foundation of movement that you enjoy.

His strength training focuses on full-body movements combined with conditioning work, such as short sprints, weighted ruck hikes or zone-2 cardio, a low- to moderate-intensity exercise that keeps the heart rate at around 60% to 70% of its maximum.

An older man walking along a rural path wearing a blue jacket, gray pants, and sneakers on a calm day.

McCastle (not pictured) recommends incorporating daily walks into your exercise routine. (iStock)

McCastle also focuses on his mobility with his hips, ankles and thoracic spine. Even on rest days, he makes it a priority to go on walks with his son.

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No. 4: Make recovery a requirement

After years of pushing his body through challenges, McCastle has found recovery to be an essential part of training.

"Sleep, hydration and mobility are just as important as training," he told Fox News Digital.

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His recovery process includes mobility work, contrast therapy, long walks and plenty of sleep. He also focuses on mental recovery through activities like journaling and spending time with his son.

"Recover with as much intention as you train," he advised.

No. 5: Keep nutrition simple

When it comes to nutrition, McCastle says that consistency beats perfection. His approach is built around whole foods, balance and consistency.

"I keep it straightforward: whole foods, protein at every meal, and enough calories to fuel training and recovery. Lots of water. Minimal processed sugar," he said.

A healthy salad bowl with grilled chicken, avocado slices, cherry tomatoes, red onion, chickpeas, and lettuce on a rustic wooden table.

McCastle prioritizes whole foods, especially protein, and makes sure he hits his daily calorie intake to fuel his body. (iStock)

McCastle avoids strict diets, instead focusing on habits that last. "I'm not dogmatic — what matters is something you can stick to."

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For those who want to add supplements to their diet, he suggests electrolytes, creatine, omega-3s, vitamin D, collagen protein and a greens powder.

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Overall, McCastle focuses on maintaining healthy habits, staying consistent and moving with purpose.

"Longevity is the goal," he said. "Strength isn’t about breaking yourself down — it’s about building something that lasts."