On Turning 40

On November 5th, I entered my 40th year on this humble planet.
It seems that a lot of people imbue a great significance to this age, like 40 is the official marker of grown-up-adulthood. While I generally feel that using age as a way to define people is minimizing, turning 40 holds some import to me. Mostly, it inspires humility. In one breath I feel like "40" is meaningless but in the next, I feel like, "Holy sh*t, I'm still here."
While I cannot verify the true source, the following bit of internet wisdom speaks loudly to me.
"Do not regret growing older. It is a privilege denied to many."