Atmarama means one who is satisfied with his self. He is called atmarama. Because self is the basic principle of this body, the soul, so one who is satisfied with his soul, he is called atmarama, or self-realized person. One who seeks pleasure externally, he is materialist, and one who seeks pleasure internally, he is spiritualist. That is the difference.

Material pleasure is circumstantial, in contact with this body. Similarly material distress. So those who are atmarama, enjoying in the platform of soul, they are not concerned with this external pleasure and pain.

From Srila Prabhupada’s lecture on Bhagavad-gita 5.17-25 — 8 February, 1969