Are used to have this challenge also. Here's what I did: come up with two simple phrases, one to describe the problem and the other a desired response to the problem. For example, my phrases were "jaw tight" & "go slack." When you think of it during the day, and possibly just before sleep, briefly clench your jaw/grind your teeth while saying to yourself "jaw tight." Immediately after, relax your jaw and facial muscles while saying to yourself "go slack." The idea is to "program" your body to automatically follow the undesirable action with the desired one. Good luck!