These articles always seem to ignore quality of life - they assume that more life is necessarily a better thing. I'm sure I'm not alone in thinking that an extra ten years of life isn't much to look forward to if your mental and physical faculties are degraded to the point that you're a shadow of your former self. Better to burn out than fade away...?
You're assumption is that you get a fixed amount of functional life, followed by a variable amount of less- or non-functional life. OTOH, you might get a variable amount of functional life, followed by a more-or-less fixed amount of non-functional life. In general, I think the second option more closely matches how we understand aging and disease.
(Also, watch the TED talk by the referenced professor. He doesn't ignore quality of life.)
Why are you concerned? Things we have always known are healthy- vegetables, moderate activity levels, etc- tend to improve your quality of life too.
It isn't like all humans, upon hitting 80, automatically have low quality of life. My grandparents are not as spry as me, but they are always cheerful and probably get out more than I do.
