At 101 years old, Dr. John Scharffenberg drives a red Toyota Prius and is a YouTube star, sharing healthy living tips he himself follows, like intermittent fasting and eating a plant-based diet.

The physician, who is an adjunct professor at Loma Linda University’s school of public health, travels the world to give lectures about living longer with simple lifestyle changes.

He was in Madagascar last summer, Europe in the fall and has been invited to talk in Las Vegas this year.

Longevity doesn’t run in Scharffenberg’s family — his mother died in her 60s from Alzheimer’s disease, and his father of a heart attack at 76 — so genes aren’t a factor helping him live beyond 100, he says.

The centenarian has also outlived his two brothers, which he attributes to being much more active than they were.

“The main difference was I got a tremendous amount of exercise,” Scharffenberg, who lives with his son in North Fork, California, tells TODAY.com.

“The time of life you get it is what’s important — middle age, from 40 to 70. That’s when you need it, because that’s the time when people usually relax, have more money, buy more food, sit around more, eat more ... and that’s the wrong way to go.”

Cardiovascular disease, including heart attack and stroke, is the main culprit cutting people’s lives short, Scharffenberg points out. It’s the leading cause of death around the world — but most cases can be prevented with lifestyle, according to the World Health Organization.

The centenarian has been spreading that message on YouTube channels like Viva Longevity! — attracting millions of views.

Scharffenberg says people can live longer by following these seven lifestyle rules:

Don’t use tobacco

The 101-year-old doctor has never smoked. Smoking harms most every organ in the body and is the leading preventable cause of disease, death and disability in the U.S., the Centers for Disease Control and Prevention notes.

Don’t drink alcohol

Scharffenberg says he’s never drunk alcohol. The notion that light drinking is good for health is not true, he notes, pointing to studies that show any protective effects for the heart are offset by an increased cancer risk — a link highlighted by the U.S. surgeon general this year.

No amount of alcohol is truly safe, experts say, echoing the World Health Organization's guidance.

Exercise

“Even though I’m a nutritionist, I think exercise is even more important than nutrition,” Scharffenberg says. It doesn't have to be running a marathon, he adds.

His main form of exercise during middle age — the time of life he urges people to be especially active — was working on a large, forested property he bought in the mountains north of Fresno. It required him to clear land for a road and a house, and then cultivate a 2-acre garden that included 3,000 strawberry plants, 80 fruit trees and grape vines.

“I did it all by myself, so I exercised a lot,” the centenarian recalls. “I worked hard.”

His go-to activity was gardening, but Scharffenberg says walking is another great exercise — TODAY's Al Roker credits walking with saving his life.

Scharffenberg points to a study that found people who walked more than 2 miles a day had only half the death rate of those who walked shorter distances.

Maintain a healthy weight

Being overweight or having obesity raises the risk of Type 2 diabetes, high blood pressure, heart disease and cancer, according to the National Institutes of Health.

The risk of health problems starts when a person is very slightly overweight and only increases from there, the World Health Organization warns.

One of the reasons Scharffenberg believes he’s outlived his brothers is that he practices intermittent fasting and eats two meals a day — breakfast and lunch. He skips dinner, so he stops eating in the early afternoon and doesn’t consume food until 6:30 a.m. the next morning.

Intermittent fasting can help with weight loss and is linked with health benefits, studies have found.

Eat less meat

Scharffenberg is a member of the Seventh-Day Adventist Church, which recommends a well-balanced vegetarian diet.

The centenarian says he hasn’t eaten any meat since he was 20 years old. He follows a plant-based diet that includes milk and eggs. Scharffenberg’s favorite foods include fruits like mangoes and persimmons, macadamias and other nuts, and seeds. He also likes potatoes.

Eat less sugar

The average American eats about 22 teaspoons of added sugar a day, which can lead to obesity, heart disease and other health problems, studies have found.

The American Heart Association recommends no more than 6 teaspoons of added sugar per day for women, 9 teaspoons for men.

Look for ways to modify recipes to eat less sugar, Scharffenberg advises. He likes waffles made with oats, a healthy recipe his wife created. Instead of drenching them in sugary syrup, she’d serve them with cashew cream and bananas or berries on top.

The sugar in fruit provides energy in a healthy way because it comes with many other nutrients, like fiber, vitamins, minerals, antioxidants and plant compounds, says registered dietitian Natalie Rizzo, nutrition editor for TODAY.

Eat less saturated fat

The American Heart Association recommends getting less than 6% of calories from saturated fat, which essentially means a vegetarian diet, Scharffenberg says.

"The optimum diet is the vegetarian diet," he tells audiences during his lectures.

"I pray that all of you will live the right lifestyle.