The guidance for handling any of life's frustrations is often some version of "have a positive attitude."

Not connecting with any of your dates? Stop being so judgmental. Floundering after a cross-country move? Try being more open and practice gratitude.

Staying positive is also a key piece of advice for anyone hoping to live a long, healthy life.

Centenarians, or those who reach 100 years old, frequently credit their lengthy lifespan to their positive attitude. 

Ruth Sweedler, 103, told CNBC Make It that she was always praised for her good attitude growing up. "When I walked into a classroom, my teacher would say, 'Good morning, sunshine!' because I was so cheerful," she said. Madeline Paldo, 100, said she doesn't get stressed much because "everything can be solved."

Personality can be a "big factor" when it comes to longevity, says Petr Sramek, CEO of Healthy Longevity Clinic, a medical practice that seeks to extend clients' lives. 

But it's less about being positive as it is about taking care of yourself. Those with longer-than-average lifespans are usually more conscientious and willing to heed medical advice.

'You cannot fix the biology without fixing the mental problems'

Part of the Healthy Longevity Clinic's treatment is creating a "road map" of habits or procedures for clients based on different biomarkers, such as blood pressure or DNA. In order for the road map to work, however, a client has to be willing to change. 

"If someone is in a state of mind that their health is out of their control, there is nothing much we can do because the person will not follow the guidance," Sramek says. 

If someone is open to changing, then successful treatment could improve their mood and make them even more open to other guidance.  

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Let's say a client has chronic inflammation, Sramek says. 

"If there is a high level of inflammation, the body is in a fight mode, which means it affects the mood," he says. "The person is still fighting something even though that is part of biology." 

If a person finds a way to subdue some of the inflammation, they might, in turn, become a more agreeable person. But they must possess the type of personality that is willing to seek and accept help. 

"You cannot fix the mental problem without fixing the biology but vice versa — you cannot fix the biology without fixing the mental problems," he says. 

'Psychologically healthy people have a quicker recovery time'

This doesn't mean positivity has no effect on lifespan. 

"Stress can negatively influence your health," says David Watson, a professor of personality psychology at the University of Notre Dame. 

A positive person might be better able to handle stressful situations. 

"Psychologically healthy people have a quicker recovery time," he says. "They are able to tell themselves, 'This is not that big of a deal.' They find ways to bring themselves back into that equilibrium." 

But the personality trait more linked to longevity is conscientiousness, or the ability to be organized and diligent. 

Conscientious people are better at taking care of themselves and are more likely to keep up with medical appointments and curb bad habits. For example, they tend to drink alcohol in moderation and eat more balanced meals, Watson says. 

"Conscientious people don't do stupid things so they have lower rates of accidents and better health behaviors," he says.

You can increase your conscientiousness with age. There are even conscientiousness workshops that seek to increase a person's ability to self-regulate, Watson says.

"The basic idea is if you want to increase your conscientiousness, act more conscientious, and the attitude follows the behavior," he says. "Try to be on time for things. Follow through on things."

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