make it business to
make it one's business to (do something)and 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.) 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.
make it your business to do something
to decide you will take responsibility to do something He made it his business to find out what happened to the money.