to put forth or into use, as power; exercise, as ability or influence; put into vigorous action: to exert every effort.
2.
to put (oneself) into strenuous, vigorous action or effort.
Origin: 1650–60; < Latinex(s)ertus, past participle of exserere to thrust out, equivalent to ex-ex-1 + ser(ere) to bind together + -tus past participle suffix
1640s, from L. exertus, pp. of exerere "thrust out, put forth," from ex- "out" + serere "attach, join" (see series). Related: Exerted; exerting. Exertion in the sense of "vigorous action" is from 1777.