Keep saying it over and over pronouncing the ‘r’ sounds. Record yourself saying it if you have to. This way you find out what it is that makes you sound the way you do, ie the way your mouth shapes when you say certain words.

(An old friend of mine moved down to NC from Boston and we made her lose her Boston accent. Now she’s a southern belle like us, saying “y’all” and everything.)

It’s hard to lose your accent, but it helps to watch other people, so watch movies or TV where people don’t have a northern accent and notice the way they talk and mimick them.

Rent “My Fair Lady” (Rex Harrison). Check out how she loses her cockney accent (so boston southie) and you can too!