Long before Bryan Johnson became famous for his extreme biohacking—undergoing countless tests, following strict eating habits, and taking dozens of supplements in the name of living forever—Valter Longo was obsessed with longevity. In a recent profile of the scientist in the New York Times, Longo, who is a professor of gerontology and director of the USC Longevity Institute in California, says he wants to live 120 to 130 healthy years. His drive for longevity aligns with a growing interest in extending health span, the number of years lived free of disease, as opposed to life span—which refers to the number of years lived.