Mental activities under the influence of material nature cause happiness and distress within the material world. Being covered by illusion, the living entity eternally continues conditioned life under different designations. Such living entities are known as nitya-baddha, eternally conditioned. On the whole, the mind is the cause of conditioned life; therefore the entire yogic process is meant to control the mind and the senses. If the mind is controlled, the senses are automatically controlled, and therefore the soul is saved from the reactions of pious and impious activity. If the mind is engaged at the lotus feet of Lord Kṛṣṇa ( sa vai manaḥ kṛṣṇa-padāravindayoḥ ), the senses are automatically engaged in the Lord’s service. When the mind and senses are engaged in devotional service, the living entity naturally becomes Kṛṣṇa conscious. As soon as one always thinks of Kṛṣṇa, he becomes a perfect yogī, as confirmed in Bhagavad-gītā ( yoginām api sarveṣāṁ mad-gatenāntarātmanā ). This antarātmā, the mind, is conditioned by material nature. As stated here, māyā-racitāntarātmā sva-dehinaṁ saṁsṛti-cakra-kūṭaḥ: the mind, being most powerful, covers the living entity and puts him in the waves of material existence.