Your mind needs the understanding and experience of how emotions or moods operate in order to not get so stressed and afraid of them when they arise. You can't control the initial snap judgment that leads to that emotional reaction, but you can control how you're going to understand and relate to the feeling or mood once it's here. Is it going to be with the attitude of, "Oh I hate this, this is going to last forever," or "Let's see how long this lasts." One is a mindless approach; the other is a more mindful approach.
But without automatically judging the mindfulness approach as better, why not see for yourself and let your experience be your teacher? Try this out and let us know what you find. How long does it last? What shape does it take in your body and what happens to it over time? Does the sensation in the body change or stay the same? Does it move somewhere else? Does a color come to mind and does that shift or stay the same? Allow this to be an opportunity to, as Derek Walcott says in him poem "Love After Love," "reintroduce the stranger who was yourself."