Beware of equating "mindfulness" with "policing your own thoughts." Being mindful is simple and straightforward - as one of my mentors is fond of saying, being mindful is about becoming as dumb as a stick. You just notice. Notice what you think, notice what you feel in your body, notice what is going on around you. Not easy to do when your inner chatterbox is busy tossing judgments, assessments and interpretations around like the expert juggler s/he is. And yet it is possible to just notice that, too. Notice how quickly you leap to conclusions, make assumptions, issue verdicts, pile up adjectives.
Policing and controlling your own thoughts is an exercise in futility. The best you can hope for is to identify the patterns of thought and behavior that don’t serve you, interrupt those pattern, and choose to do something else. If you do that often enough, eventually your thoughts will change. It works, it just takes practice.
The key, of course, is you have to notice the patterns before you can interrupt them, which brings you right back to mindfulness – to noticing.