A multi-decade Harvard study tracking hundreds of men found the quality of relationships was the single best predictor of long-term health and life satisfaction. People most satisfied with their relationships at age 50 were the healthiest at age 80, a stronger correlation than with social class, wealth, fame, or genetics.

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.

Research on millions of people reveals that having strong social relationships reduces mortality risk by 20-30% in later life, an impact that significantly outweighs the benefits of diet, exercise, and sleep.

A major transformation has occurred in longevity science, particularly in the last eight years. The conversation has moved away from claims of radical life extension towards the more valuable goal of increasing "healthspan"—the period of healthy, functional life. This represents a significant and recent shift in scientific consensus.

Despite the emphasis on genes from the Human Genome Project era, large-scale modern studies show genetics determine only about 7% of how long you live. The remaining 93% is attributable to lifestyle, environment, and other non-genetic factors, giving individuals immense agency over their lifespan.