gird (up) one’s loins, to

To prepare for action (hard work, a journey, warfare). The term comes from the Bible, both Old and New Testaments, and uses gird in the sense of “encircle with a belt or band.” The ancient Jews wore loose clothing and put on a girdle, or belt, only when they went to work or set out to travel. Thus, “He girded up his loins, and ran” appears in I Kings (18:76), and “Gird up now thy loins like a man” in Job (in several passages). It had already become figurative in the New Testament, where 1 Peter has it, “Gird up the loins of your mind, be sober” (1:13).