Mindfulness refers to keeping one’s consciousness alive to the present reality
Zen Master Thich Nhat Hanh
Mindfulness is to carry out an action, intentionally, in the present moment, without judgement. It is simply the practice of awareness, or ‘being present’. There can be an internal focus (e.g. mindfulness of the mind or the body) or an external focus on activities (e.g. washing the dishes, cooking a meal).
Mindfulness is a simple and natural thing. There’s nothing special to believe in. We just do it.