1
general::
Phrase(s): He who hesitates is lost.
Prov. People should act decisively. • Jill: Should I apply for that job? At first I thought I definitely should, but now I don’t know. . . . Jane: She who hesitates is lost. • Call that girl and ask her out. Call her right now. He who hesitates is lost.
McGrawhill's American Idioms And Phrasal Verbs
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general::
One who cannot come to a decision will suffer for it, as in I couldn't make up my mind, and now the offer has expired? he who hesitates is lost. Although the idea is undoubtedly older, the present wording is a misquotation or an adaptation from Joseph Addison's play Cato (1712): "The woman that deliberates is lost."
American Heritage Idioms