Mindfulness is attending to what is happening in the moment, inside and outside ourselves, instead of always thinking about the future or the past. Some people find it a useful way of feeling more connected to their bodies, thoughts and feelings. It can take a bit of practice, but even some simple breathing exercises can help some people feel more present and calmer.
I try to use mindfulness or a simple form of meditation to bring me back in the present time.
If I am having intrusive thoughts I try mindfulness exercises like naming everything around me or describing the space around me non judgmentally.
I practice breathing exercises if a situation triggers a panic attack.