yada mana upadaya
yad yad rupam bubhusati
tat tad bhaven mano-rupam
When the yogi, applying his mind in a certain way, desires to assume a particular form, that very form immediately appears. Such perfection is possible by absorbing the mind in the shelter of My inconceivable mystic potency, by which I assume innumerable forms.
This perfection is called kama-rupa, or the ability to assume any form that one desires, even the form of a demigod. The pure devotees absorb their minds in a particular type of service to Lord Krsna and thus gradually assume a spiritual body for an eternal life of bliss and knowledge. Thus anyone who takes to the process of chanting the holy names of Krsna and follows the regulative principles of human life can acquire the ultimate perfection of kama-rupa, assuming an eternal, spiritual body in the kingdom of God.