Mindfulness involves paying attention “on purpose”. Mindfulness involves a conscious direction of our awareness. We sometimes (me included) talk about “mindfulness” and “awareness” as if they were interchangeable terms, but that’s not a good habit to get into. I may be aware I’m irritable, but that wouldn’t mean I was being mindful of my irritability. In order to be mindful I have to be purposefully aware of myself, not just vaguely and habitually aware.
Left to itself the mind wanders through all kinds of thoughts including thoughts expressing anger, craving, depression, revenge, self-pity, etc. As we indulge in these kinds of thoughts we reinforce those emotions in our hearts and cause ourselves to suffer. Mostly these thoughts are about the past or future. The past no longer exists. The future is just a fantasy until it happens. The one moment we actually can experience the present moment is the one we seem most to avoid.
TB