In Nonviolent Communication you will find an amazingly effective language for saying what's on your mind and in your heart. Like so many essential and elegant systems, it's simple on the surface, challenging to use in the heat of the moment and powerful in its results.
That which occasions so many mistakes in the computations of men, when they expect return for favors, is that the giver's pride and the receiver's cannot agree upon the value of the kindness done.