paying attention non-judgementally, with openness, curiosity and flexibility.
Mindfulness can be a narrow focus, broad focus, inner focus or external focus, it is a shifting flexible focus.
Mindfulness can give rise to relaxation as a byproduct, however mindfulness is not trying to change your feelings or change your experience for better ones. Feelings are as they are. Mindfulness brings our attention to how our body is feeling and what our mind is thinking. We can know ourselves more fully.
Other terms for Mindfulness
We have no control over what thoughts and feelings arise in us (we certainly put a lot of effort in trying to change how we feel and our state of mind). Mindfulness allows us to step back from our thoughts and feelings and see them clearly so they are less overwhelming and have less impact over us.