What is "to exert one's self"

Exert \Ex*ert"\, v. t. [imp. & p. p. Exerted; p. pr. & vb. n. Exerting.] [L. exertus, exsertus, p. p. of exerere, exserere, to thrust out; ex out + serere to join or bind together. See Series, and cf. Exsert.]

1. To thrust forth; to emit; to push out. [Obs.]

   So from the seas exerts his radiant head The star by whom the lights of heaven are led.
   --Dryden.

2. To put force, ability, or anything of the nature of an active faculty; to put in vigorous action; to bring into active operation; as, to exert the strength of the body, limbs, faculties, or imagination; to exert the mind or the voice.

3. To put forth, as the result or exercise of effort; to bring to bear; to do or perform.

   When we will has exerted an act of command on any faculty of the soul or member of the body.
   --South.

   To exert one's self, to use efforts or endeavors; to strive; to make an attempt.