Enthusiasm- That (spiritual) strength of the prāṇī (living being or soul, possessed of vital energy), through which it prepares itself for accomplishment of a work.
utthānaṃ- ceṣṭāviśeṣaḥ.
(SthāVṛ Pa 21)
utthānaṃ- ūrdhvībhavanam.
(Bhaga 1.146 Vṛ)