People used to strive simply to live as long as possible, but in recent years, that goal has taken on a new dimension: How long can you live in good health? “The focus now is on health span, not life span,” said Dr. Frank Lipman, a co-author of the 2020 book “The New Rules of Aging Well.” “We generally talk about extending someone’s life, but what’s the use if they’re suffering and disabled and can’t enjoy what they have?”