When most people hear “longevity,” they think of living to 90 or 100. But in the longevity world, there are actually two very different ideas at play: lifespan and healthspan.

Lifespan is the total number of years you’re alive, from birth to death. Healthspan is the number of those years you spend in good health—free from major disease or disability, able to live life on your terms. You can have a long lifespan but a short healthspan (decades with chronic illness), or a shorter lifespan but a long healthspan (fewer years, but lived with energy and independence).

The big shift in modern longevity is this: we’re no longer just asking, “How can I live longer?” but “How can I live better for as many years as possible?” Globally, people now spend roughly 8–10 years, on average, in poor health at the end of life—years that often involve limited mobility, chronic disease, or loss of independence. That “gap” between lifespan and healthspan is what researchers, clinicians, and serious hobbyists are trying to close.

So when you see headlines about longevity drugs, anti-aging tech, or “reversing biological age,” a useful question to ask is: Is this mainly about adding years to my life—or life to my years? The most robust evidence so far points to very down-to-earth levers—movement, nutrition, sleep, stress, and social connection—as powerful ways to extend healthspan, not just lifespan.

If you want to go a little deeper on this distinction, this short explainer from Harvard Medical School is an excellent, plain-English overview of the move “From life span to health span” that you can read here: From Life Span to Health Span – Harvard Medical School.