Centering
Centering and grounding are words that human beings refer to when they are feel anchored in the present moment. We could say that time is non-existent and that only the moment of Now is present. Let us say that every time you as an individual human being is focused on the past or the future, you are moving your energy and awareness into something that is non-existent. When you as an individual human being direct your attention to many things at once, you lose your center point or single focus awareness.
Centering oneself is a practice or technique that redirects your attention or awareness into this Now moment and a single point focus. A human being who is grounded or centered feels a sense of stability, solidness and single focused awareness in each present moment. Let us note that earthing is sometimes referred to as grounding or centering, however earthing refers specifically to electrical grounding or connection to the Earth.
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About centering:
Grounding and centering exercises:
Centering videos: