While not an essay, I'd throw Seneca's "On the Shortness of Life" into the mix. It's short and very eloquently raises ideas about what to prioritize in life.
One other addition I'd put on this list is Milton Glaser's talk "What I have learned", delivered on November 11, 2001, in London. Copies of it are floating around.
I’ve always liked this Saturday Morning Breakfast Cereal cartoon as a reminder to get out of ruts.
I have read "Life is Short" countless times.
Great list! Overlaps somewhat with my own (incidentally also titled “life advice”): https://trove.to/wes/trove/de40440b-ed21-4fdb-ba61-b5f83322b...