There are plenty of guidelines for physical fitness — from getting in 10,000 steps to drinking eight glasses of water every single day — but we aren't often given recommendations for keeping your social life in good health.

Kasley Killam, a Harvard-trained social scientist and leading expert in social health, came up with a social workout plan that people can use to maintain their social fitness. Killam detailed the method in her recently published book, "The Art and Science of Connection."

"The 5-3-1 guideline is meant to be like a reference point for people," Killam tells CNBC Make It. Just like the recommendation of sleeping for eight hours a night, the 5-3-1 guideline is a research-based suggestion.

Use the 5-3-1 guideline to maintain meaningful connections

The 5-3-1 guideline states that you should:

• Connect with five different people each week
• Maintain at least three close relationships
• Get one hour of quality interaction each day

"Again, this is a guideline, right? Those numbers might be high or low for a given person," Killam says.

"If you're more extroverted, they might seem too low. If you're more introverted, they might seem a bit high," she adds. "But in general, drawing from the research on the amount of time and amount of relationships that people have who are really thriving, that's a great starting point."

An ongoing Harvard study that began in 1938 discovered that the No. 1 thing that leads to a happier, longer life is social fitness. The study includes health records from over 700 participants.

Social fitness is the act of maintaining healthy, balanced personal relationships, according to Marc Schulz and Robert Waldinger, directors of the Harvard Study of Adult Development.

Schulz and Waldinger say that, ideally, you should have someone, or several people, that can support you in each of these areas:

• Learning and growth
• Safety and security
• Identity affirmation and shared experience
• Emotional closeness and confiding
• Romantic intimacy
• Fun and relaxation
• Help (informational and practical)

"Don't be afraid to reach out to the people in your life," the Harvard study directors wrote in a Make It article in February of 2023.

"Whether it's a thoughtful question or a moment of devoted attention, it's never too late to deepen the connections that matter to you."

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