Dr. Sanjay Gupta, CNN’s Chief Medical Correspondent, recently shared the three pieces of advice he wished he knew when he was younger.

The main theme: Aging isn’t necessarily bad. “I have learned so much about getting older, the myths and the realities, and what it takes to be in the best physical and mental condition during any stage of life,” Gupta, 53, said in his article for CNN.com.

Below are the three things Gupta said are important for living a long, healthy, and happy life.

1. Talk to people who are older

Gupta said you can learn a lot from asking older people about their routines — especially if they’re in great health.

When he interviewed his mother, he learned that she sleeps 8-9 hours a night, tries not to dwell on negative thoughts, and keeps active throughout the day with walks, water aerobics, and having friends over.

He also has friends over 60 who are constantly moving and challenging their bodies the same way they did when they were in their 30s. As a result, they don’t feel the same stiffness and pain other people their age do.

Gupta said that talking to them paints “a much more optimistic picture” about aging.

2. Have a positive attitude towards aging

Gupta believes we live in a “youth-centric society” where we focus more on anti-aging than embracing old age.

But clinging to youth isn’t just a waste of time: It can actually make us sicker. Citing a 2002 study, Gupta said that people with positive views of aging lived 7.5 years longer on average than those with negative attitudes. Negative age stereotypes were also linked to higher risks of cardiovascular disease and Alzheimer’s.

He said one way to challenge negative beliefs about aging is to spend more time with grandparents and other older adults, even if you don’t live in a multi-generational home. It helps to push back against the idea that being old means you’ll be forgotten about and just tucked away in a nursing home.

3. Take good care of your body

It’s hard to have a positive attitude about aging if you just don’t feel good. That’s why Gupta said staying in good physical health is key. To him, that means “eating right, not smoking, getting enough sleep, drinking in moderation (if at all), reducing stress, interacting with family and friends, and engaging in regular exercise.”

As you get older, he also emphasized weight training and fast-twitch exercises to help maintain strength and prevent falls.

He also said that it’s never too late to start healthy habits: He’s met people in their 70s who first started moving around more or becoming more social — only to see a meaningful impact on their lives.