I wish I could remember the book or author, but I remember reading a scifi story some years ago in which a main part of the world was indefinitely extended life

I wish I could remember the book or author, but I remember reading a scifi story some years ago in which a main part of the world was indefinitely extended lifespans and health-spans. A couple of items that shifted the readers' perspective were the 28 year old character who misstated her age as 104 to make herself seem more interesting, and that many people in the 400-500 year-old range picked up high risk sports as out of growing boredom with multiple careers and pursuits... (if anyone recognizes and remembers the story, it'd be great to know what it is!)