Cicero, like many other philosophers of antiquity, places ultimate value on the goal of 'a life well-lived'. In this essay, he basically says 'old age is fine, if you lived a good life beforehand', and hedges by saying death's no big deal.
Which is, of course, rubbish. That's not really how life works: rewards rarely follow your efforts to live a good life. There are often no rewards at all; a life of diligent savings can disappear in an instant, physical fitness can end with cancer, faithfulness can end in bitter disappointment. Attempting to 'optimize' your life, your finances, your career often put you in places you never wanted to be.
The Buddhists come closer to what life is really about: life is not a journey, it's a dance. And you can dance anytime; old age can be joyous anytime you choose to dance--you don't need a 'good life' preceding it to make it good. Or, TL;DR: All you ever have in life is this one moment, right now.