SB 3.25.16

ahaṁ mamābhimānotthaiḥ
 kāma-lobhādibhir malaiḥ
vītaṁ yadā manaḥ śuddham
 aduḥkham asukhaṁ samam
Synonyms: 
aham — I; mama — mine; abhimāna — from the misconception; utthaiḥ — produced; kāma — lust; lobha — greed; ādibhiḥ — and so on; malaiḥ — from the impurities; vītam — freed; yadā — when; manaḥ — the mind; śuddham — pure; aduḥkham — without distress; asukham — without happiness; samam — equipoised.
Translation: 
When one is completely cleansed of the impurities of lust and greed produced from the false identification of the body as “I” and bodily possessions as “mine,” one’s mind becomes purified. In that pure state he transcends the stage of so-called material happiness and distress.
Purport: 

Kāma and lobha are the symptoms of material existence. Everyone always desires to possess something. It is said here that desire and greed are the products of false identification of oneself with the body. When one becomes free from this contamination, then his mind and consciousness also become freed and attain their original state. Mind, consciousness and the living entity exist. Whenever we speak of the living entity, this includes the mind and consciousness. The difference between conditional life and liberated life occurs when we purify the mind and the consciousness. When they are purified, one becomes transcendental to material happiness and distress.

In the beginning Lord Kapila has said that perfect yoga enables one to transcend the platform of material distress and happiness. How this can be done is explained here: one has to purify his mind and consciousness. This can be done by the bhakti-yoga system. As explained in the Nārada-pañcarātra, one’s mind and senses should be purified (tat-paratvena nirmalam). One’s senses must be engaged in devotional service to the Lord. That is the process. The mind must have some engagement. One cannot make the mind vacant. Of course there are some foolish attempts to try to make the mind vacant or void, but that is not possible. The only process that will purify the mind is to engage it in Kṛṣṇa. The mind must be engaged. If we engage our mind in Kṛṣṇa, naturally the consciousness becomes fully purified, and there is no chance of the entrance of material desire and greed.