Aristotle argues that the most important form of happiness consists neither in momentary episodes of pleasure nor in long series of such moments,but rather in the happiness one can take in old age in reflecting back on a life well-lived. In your own words, What, according to Aristotle, constitutes a life well-lived, and how does his conception of this relate to his conception of virtue and his ideal of virtuous action that avoids both "excess" and "deficiency" but rather that realizes "a mean"?