"Those who are cultivating spiritual life and executing devotional service are always engaged in activity. Such activity can be performed with the body or with the mind. Thinking, feeling and willing are all activities of the mind, and when we will to do something, the activity comes to be manifest by the gross bodily senses. Thus, in our mental activities we should always try to think of Kṛṣṇa and try to plan how to please Him, following in the footsteps of the great ācāryas and the personal spiritual master. There are activities of the body, activities of the mind and activities of speech. A Kṛṣṇa conscious person engages his words in preaching the glories of the Lord. This is called kīrtana. And by his mind a Kṛṣṇa conscious person always thinks of the activities of the Lord—as He is speaking on the Battlefield of Kurukṣetra or engaging in His various pastimes in Vṛndāvana with His devotees. In this way one can always think of the activities and pastimes of the Lord. This is the mental culture of Kṛṣṇa consciousness."