Aamritat-Tvamichan means desiring immortality, wanting to overcome death. The first thing is to withdraw from the outside world and then you become aware of the body. We draw further into thoughts by quietening the mind down with a mantra or turning inwards to the self. It has to be done in multiple stages.
Swami Sarvapriyananda teaches Chapter 6 (Verses 26-27) of the Bhagavad Gita. In this series of talks, Swami Sarvapriyananda unfolds the highest truths of Vedanta through the study of the Bhagavad Gita (The Song of God).