When you notice an unhelpful emotion or a shift in mood, or when you notice that you're doing something you know can cause problems (being snappy, for example, or drinking too much), that could act as a cue to examine your own thoughts - "what am I thinking?".

The New Laws of Psychology: Why Nature and Nurture Alone Can't Explain Human Behaviour (ed. Hachette UK, 2014) - ISBN: 9781780336015