Euploea Core

The mind is fickle, and therefore it is necessary to engage the mind by force to think of Kṛṣṇa. One example often given is that of the caterpillar that thinks of becoming a butterfly and so is transformed into a butterfly in the same life. Similarly, if we constantly think of Kṛṣṇa, it is certain that at the end of our lives we shall have the same bodily constitution as Kṛṣṇa.
(BG 8.8)