An ungenerated part of the vital nature.
It is not a matter of any particular act or feeling, but a sort of excited vibration with which the vital and physical consciousness meets the vital disturbance — it is evident in the tone and language of what you write when there is the stress of vital suggestion — but it used also to rise when you got the experiences in excited vibration and bubbling of joy which would easily lapse into some rajasic movement or be replaced by the opposite excitement of suffering and disturbance. Quiet, quiet and more quiet, calm strength, calm gladness are what are needed in mind and nerves and body as a basis for the siddhi, precisely because the Force, the Light, the Ananda that come down are extremely intense and need a great stillness in the body to bear and support.
About living and doing all for oneself, but that is the nature of man, he is centered in his ego, ego-centric, and does all for his ego; even his love and liking is mostly based on ego. All that has to be changed and all has to be centered in the Divine, done for the Divine Mother. It is the work of the sadhana to get that done. The silence, the growth of the psychic and all else is meant to bring about that, but it cannot be done all at once. When the consciousness is ready, then the psychic love, the impulse for self-giving begins to open out in the heart and the change is made — more and more till there is the complete self-giving.