The trick is to become more and more resentful about how you are being used until that feeling is stronger than the stubbornness that won't let things drop. ;)
One of my key issues is being (sorry for the technical medical terminology here) a bit of a manic depressive fuckwit. Manic me gets big ideas & plans things, and being all excitable he tells everyone about said intentions so that the rest of me then feels the need to find a way of making happen! I do it to myself more than there being other people to be resentful of.
