I'll add to this that if I want to avoid the "backfire" scenario, one useful technique is to be seen as actually changing the behavior that I promised to change.

The period over which the changed behavior must be sustained in order to placate suspicious observers depends significantly on how suspicious they are, so it's often best to do this before I notice them becoming overtly suspicious... that is, to establish a habit of following up my promise to change my behavior with an actual change in my behavior.