An 85-year Harvard study on adult life revealed that the strongest predictor of long-term health and happiness isn't wealth, fame, or power, but the quality of close relationships. Having even one person to count on is the key protective factor for a good life.

The longest-running study in psychology revealed that the single most significant factor for long-term health, happiness, and longevity is the quality of one's relationships. This factor was more predictive than wealth, career success, or even baseline health, underscoring its foundational importance for leaders.

While physically detrimental, alcohol's benefit in facilitating social interaction—a powerful mitigator of mortality risk—can outweigh its harms when consumed moderately in social settings, not alone or to excess.

There is a plateau effect for exercise benefits. After 2.5 to 5 hours of vigorous activity per week, more exercise does not increase lifespan. This time could be better used for other meaningful activities like volunteering or socializing, which also contribute to well-being.

Physical health is often a lagging indicator of mental and emotional well-being. Chronic health problems can persist despite rigorous diet and exercise but may resolve "magically" once you align your life with meaningful work and strong relationships. The mind and body are deeply connected.

Our brains evolved to equate social isolation with a mortal threat, triggering a physiological stress response. This elevates cortisol and causes chronic inflammation, leading to severe health consequences, with studies showing isolated individuals are 32% more likely to die from any cause.

The severity of clinical dementia is not solely determined by neurological damage. Social factors like relationships, environment, and family support—termed "psychosocial reserve"—can be as crucial as neuropathology, explaining why some individuals with significant brain damage remain cognitively intact while others decline rapidly.

A home’s value for longevity is deeply tied to its micro-community. The ability to walk to get fresh food, see friends, or enjoy entertainment draws people outside, fostering the natural activity and social connection that are critical for health but often overlooked.

Contrary to the 'lonely spinster' stereotype, men lacking romantic partners are more prone to substance abuse and other unproductive behaviors. Men in relationships also live significantly longer, suggesting they benefit more from the partnership's 'guardrails.'