nail in one's coffin

Idioms  

1. Something that might hasten or contribute to one's death, as in Every cigarette you smoke is another nail in your coffin. This expression, alluding to fastening down a coffin lid, is today almost always used for a harmful habit such as tobacco use (giving rise to the slang term coffin nail for a cigar or cigarette). The idea was first expressed in an ode by Pindar (the pseudonym of John Wolcot) in 1792: “Care to our coffin adds a nail, no doubt.”

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Example Sentences

Coff′in-ship, a ship that is unsound, and likely to prove fatal to those in it.—Drive a nail in one's coffin, to do something tending to hasten death or ruin.

From Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) by Various

The old saying is, that every sigh drives a nail in one's coffin.

From The Physical Life of Woman: Advice to the Maiden, Wife and Mother by Napheys, George H. (George Henry)