A more accurate way to look at this is using the annual cycle of life rather than the calendar year. Spring clearly is birth and Winter becomes death.
Using those 80 years, Spring is birth to 20 which is closely aligned to physical human growth and development. The Summer of our lives is 20-40 where everything is meant to thrive. By Autumn, 40-60 we slowly begin our maturity, start drying and greying and wrinkling so that by Winter, 60-80 we eventually shrivel up and die.
A recent article about men's health said on average that 65 is the major turning point for cellular functioning, whereas the peak was decades prior, at around 65 there started a noticeable downward ski slope decline.
You can choose to admit it or not, but 66 is definitely within the Winter of your life. BUT as we all know, some Winters are long and drawn out and full of cozy fires and steamy sex.