Question: The appearance of Kṛṣṇa is auspicious. Why fast on such an auspicious day?
Answer by Romapada Swami:
We honor auspicious days by doing two things.
We decrease the bodily functions and increase hearing and chanting about Kṛṣṇa.
By fasting, there is the effect of controlling the senses starting with the tongue, which helps control the mind. By purifying the senses and mind, it makes us more receptive or clear to receive Kṛṣṇa’s message.
Each of the yoga systems requires, somehow or other, control of the mind and the senses.
On auspicious days, we take advantage of controlling the mind and senses, increasing hearing and chanting about Kṛṣṇa, because the day is auspicious, particularly for spiritual activities.