The legendary actress Betty White passed away on December 31 at the age of 99, just a few weeks shy of her 100^th birthday this past Monday. She was a shining example of how living a positive life filled with purpose helps boost the immune system and longevity.

“Animal companionship was critical for Ms. White,” Dr. Robert Lahita, author of Immunity Strong: Boost Your Natural Healing Power & Live to 100, tells Newsmax. “Every time she hugged and loved on her pets her hormone levels of oxytocin and prolactin rose and thus did her resistance to infection.” Lahita, affectionately called “Dr. Bob,” says that White knew how to de-stress herself, she ate well, and she maintained a vigorous, active life even into her elder years,

“It’s honestly amazing,” says Lahita, director of the Institute for Autoimmune and Rheumatic Disease at St. Joseph Health. “She had a curious mind and a great sense of humor and laughing a lot can help you live to 100 because it takes off stress.”

More ways to live better, long:

• Engage in moderate exercise. Extreme exercise like running marathons stresses the immune system, says Dr. Bob. “However, an exercise like taking a bike ride every day is great for immunity. I think that people should exercise every day — I certainly do,” he tells Sports Illustrated. “Don’t let your treadmill become a coat rack!”

• Practice mindfulness. Dr. Bob says that any practice that relaxes you has health benefits. He adds that there is strong evidence that meditation, tai chi, qigong, and yoga connect strongly to immunity. “I’m a big supporter of mindfulness meditation, which focuses your attention and decreases your reactivity to stressful stimuli.”

• Avoid the overuse of antibiotics. Any use of antibiotics upsets the gut microbiome which communicates with your immune system, says the expert. Taking antibiotics for a common cold is inappropriate, and the use of these drugs should be reserved for pneumonia, strep throat and other severe infections or conditions.

• Eat a plant-based diet. Eating a balanced diet that includes fruit and vegetables helps the immune system and supports longevity. People who live in the five Blue Zones around the world live statistically longer than the rest of the population, and still engage in physical activity in their most senior years —often over the age of 100. The Blue Zones are Sardinia in Italy, the islands of Okinawa in Japan, the Nicoya Peninsula in Costa Rica, the island of Ikaria in Greece, and Loma Linda, California. According to experts, what they share is a plant-based diet, a sense of community and a love of the land.

• Enjoy chocolate and garlic. According to Healthline, dark chocolate is one of the best sources of antioxidants you can find. The polyphenols, flavanols and catechins in dark chocolate have more antioxidant activity than any fruits tested, including blueberries, to protect your immune system. Dr. Bob says that garlic is also a “powerful antioxidant with antimicrobial, antiviral and some say antibiotic properties.”