- Ruth made it her business to get to know the customers.
- I know it doesn't concern me, but I made it my business to call city hall because someone had to.
- Jane took it upon herself to find out exactly what had happened to the old lady.
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■ make it your business to do something: △to make a special effort to do something.
■ make it one's business to do something (= take it upon oneself to do something): △Fig. to do something on one's own even if it means interfering in something that does not directly concern one. (As opposed to minding one's own business.)
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CF. business (as a matter): a situation or activity, often one that you are giving your opinion about:
- Arranging a trip abroad is a time-consuming business.
- These killings are a dreadful business.
- I make it my business (= I feel it is my particular duty) to check the monthly accounts.
- We've got some unfinished business to discuss (= We still have something important to discuss).
...... LDOCE, McGraw-Hill Dictionary of American Idioms and Phrasal Verbs, CALD