100-year-old marathon runner, Mike Fremont, set the fastest time for a marathon ever finished by a 91-year-old. He recently shared what he believes to be his secret to longevity in a podcast with Rich Roll.

“These, believe it or not, are the best years of my life.” You might not expect to hear that phrase out of the mouth of a centenarian, but that’s exactly what marathon runner Mike Fremont recently told author and podcaster Rich Roll.

Fremont, who was diagnosed with colorectal cancer at the age of 69, and reportedly given three months to live, turned to a plant-based diet in an attempt to help shrink the cancer. According to Runner’s World, Fremont reckons he shrunk the tumour with his new diet, before having surgery in 1994 to remove what was left of it.

“The tumor shrank over the next two years and finally I killed it by diet alone,” Fremont said, according to Runner’s World.

WATCH: Mike Fremont Explains His Secret To Longevity

Speaking to Rich Roll in a video recently posted to Instagram, Fremont says: “No question in my mind – it is diet that has determined my existence, my continual existence and my beautiful health.”

He added: “I don’t think I ever became competitive until I was 88. For my age, I’m practically number 1.”

Fremont’s elite ultramarathoner buddy Harvey Lewis has also posted about the amazing 100-year-old recently, sharing some interesting insights. He posted a photo of Fremont doing pull ups with the caption: “5 miles with my 100 year young friend Mike Fremont. Mike also did 10 pull-ups at one go!”

“Mike’s mindset is strong. He fell this past spring in Florida and hurt his hip. He was reduced to a wheel chair for a month. That was really tough especially for Mike whose always on the go. When he restarted he could only do 1 pull up. Mike credited his Plant Based nutrition with his speedy recovery even as a centenarian in getting back his distance and reps of pull-ups.”

“We finished our exercises and I asked Mike if he was done for the day. He said, I’ll probably do some more pull ups later at home.”

Harvey Lewis

What does Fremont’s diet look like? As he once claimed, according to Runner’s World in 2013: “No meat, no dairy products, no toxins.” Fremont’s diet mainly comprises veggies, fruit, whole grains, nuts and soups, plus a bit of vitamin D in winter. In that same 2013 article, Fremont said since he started eating this way he hasn’t had a cold and maintains the same weight as his university wrestling years.

Now that’s food for thought. Check out the full podcast with Fremont here.