When does being “middle aged” begin? When does one slide from being a young adult or emerging adult to an older adult?

These categories have some porous boundaries but there is another way to look at this. What is the life expectancy of people in the United States and where do I fit?
According to the CDC (2022 data), life expectancy is 77.5 for all adults and 74.8 for men. For the year I was born, the life expectancy was a little lower than the 2022 figure.
With that data in mind, I am comfortably past the mid-point of life. Sure, there are some personal traits and family history to consider but the broad data suggests this is the case.
Does this help me feel better or worse? Hard to know; it does provide a reminder that many others are in similar positions. In a society that often prizes youth and all that comes with it, to be further along in the age distributions comes with consequences.