For Jeffrey Bland, functional medicine has been "a lifetime of work," he says. In the 1980s, Bland worked for two-time Nobel Laureate Linus Pauling at the Linus Pauling Institute of Science and Medicine, where the focus was on determining what role, if any, vitamins and other macronutrients played in bettering health and preventing disease.

Bland was so impressed with the LPI's work, that in 1990 he launched the Institute for Functional Medicine in Seattle, Wash. to expand on their research with his wife, Susan.

Functional medicine is "looking at the cause of disease, not just what we call it and how we diagnose it, but also where it came from," Bland tells CNBC Make It.

With his fellow researchers, Bland set out to answer a question that could change the approach to healthcare: "Could we move to a form of healthcare where we're spending more time worrying about and focusing on how to keep a person from being sick than just treating the sick downstream?"

Developing that type of healthcare and sharing the framework with health professionals became Bland's focus for more than 30 years, and led to the launch of Personalized Lifestyle Medicine Institute, of which he is the founder and president. He spoke to CNBC Make It during the week of his 79th birthday, and shared some lessons that he's learned from his research and life experiences.

"It's been an extraordinary 79 years," Bland, who is known as the "father of functional medicine," says.

"At this age, you start to learn your body. Hopefully you've had enough years in it to start to have some wisdom about the things that are good for you, and the things that are not so good for you. So I have some rules."

5 rules the 'father of functional medicine' lives by for better health

1. I don't have relationships with anybody I don't like.
2. I don't engage in conversations that I think are degrading.
3. I don't go places I feel I shouldn't be or do things that are not in my long-term, best interest.
4. There's no excuse that I have to say that I'm having a bad day because I'm completely in charge of my day. Instead, I ask what I can do to make it better.
5. I try to remember that my presence here is to be of service to others.

In addition to those five rules, Bland also has daily practices that he says help to keep him in good health. Currently, he is focused on his sleep: "I try to make sure that when we're traveling, that I don't overstress, and I get the proper rest."

Bland is also extremely mindful of his diet, and takes Himalayan Tartary Buckwheat supplements and omega-3 fatty acids every day.

Throughout his life, Bland has prioritized time with his family, and "traveled over 6 million miles," which has allowed him to meet many people.

"I try to say, 'Okay, how can we stretch this good run? How do we make sure that we're not just talking the story, but we're walking the talk?'"

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