This handy online tool is designed by Ben Furman:
You will be asked to think about a person whose behaviour you do not approve of and you would want to change.
The program will ask you some questions and building on your answers, it will compose two different versions of how you might express yourself to the person you are thinking of.
Do add or subtract elements to the 2nd version: customise the end result of your wish to your own specific situation.
Alternatively, you may want to stick to the 1st version: how does this help to get what you want from the other?