What is "to make a thing one's business"

Business \Busi"ness\ (b[i^]z"n[e^]s), n.; pl. Businesses (b[i^]z"n[e^]s*[e^]z). [From Busy.]

1. That which busies one, or that which engages the time, attention, or labor of any one, as his principal concern or interest, whether for a longer or shorter time; constant employment; regular occupation; as, the business of life; business before pleasure.

   Wist ye not that I must be about my Father's business?
   --Luke ii. 49.

2. Any particular occupation or employment engaged in for livelihood or gain, as agriculture, trade, art, or a profession. ``The business of instruction.''
   --Prescott.

3. Financial dealings; buying and selling; traffic in general; mercantile transactions.

   It seldom happens that men of a studious turn acquire any degree of reputation for their knowledge of business.
   --Bp. Popteus.

4. That which one has to do or should do; special service, duty, or mission.

   The daughter of the King of France, On serious business, craving quick despatch, Importunes personal conference.
   --Shak.

   What business has the tortoise among the clouds?
   --L'Estrange.

5. Affair; concern; matter; -- used in an indefinite sense, and modified by the connected words.

   It was a gentle business, and becoming The action of good women.
   --Shak.

   Bestow Your needful counsel to our business.
   --Shak.

6. (Drama) The position, distribution, and order of persons and properties on the stage of a theater, as determined by the stage manager in rehearsal.

7. Care; anxiety; diligence. [Obs.]
   --Chaucer.

   To do one's business, to ruin one. [Colloq.]
   --Wycherley.

   To make (a thing) one's business, to occupy one's self with a thing as a special charge or duty. [Colloq.]

   To mean business, to be earnest. [Colloq.]

   Syn: Affairs; concern; transaction; matter; engagement; employment; calling; occupation; trade; profession; vocation; office; duty.