I've seen this posted by a few other friends who are in their early 40s. It is so deeply imbued with my own feelings of being in my 40s.
Men at Forty
Men at forty
Learn to close softly
The doors to rooms they will not be
Coming back to.
At rest on a stair landing,
They feel it moving
Beneath them now like the deck of a ship,
Though the swell is gentle.
And deep in mirrors
The face of the boy as he practices tying
His father’s tie there in secret,
And the face of that father,
Still warm with the mystery of lather.
They are more fathers than sons themselves now.
Something is filling them, something
That is like the twilight sound
Of the crickets, immense,
Filling the woods at the foot of the slope
Behind their mortgaged houses.
Donald Justice, “Men at Forty” from New and Selected Poems. Copyright © 1995 by Donald Justice. Reprinted with the permission of Alfred A. Knopf, a division of Random House, Inc.
Source: Poetry (May 1966).