When a person is attached to worldly possessions and is driven by endless desires, that person is called a Jivatma*. The Jivatma identifies with the body, with relationships, with status, and with things that are temporary and because of this attachment, the mind remains restless and bound to the cycle of endless longings and suffering.
When one turns inward through devotion, Gyan*, Yoga*, or Dhyan*, the desires begin to dissolve. By understanding the true nature of life, one realizes that the world is transient and nothing here is permanent. This realization marks the beginning of the journey toward the Aatman*, the Eternal Self. The Aatman is not bound by name, form, or time. It is Pure Consciousness, and this is what the scriptures call Sanatan* - the Eternal.
When one goes beyond the awareness of the Aatman and enters in deep meditation, one begins to experience the Avyakta*, the Un-manifested, the Undescribed. It cannot be defined in words, because it is beyond form and thought.
And when one goes even deeper, beyond the Avyakta, through intense devotion or meditation, one catches only a glimpse of the Absolute — Purusha*, Om*. This Om* is Param Aatma*, the Supreme Self, from which everything arises and into which everything dissolves.
From core, we all are that Pure Cosmic Consciousness i.e. Param Aatma who can never be preceived through the mortal five senses and if we truly want to go back to our very origin, the only thing we need to do is to stop doing anything. Stop thinking...
Reference:
Katha Upanishad