(Krsna Meditation Album by Srila Prabhupada)
paramam purusam divyam
abhyasa-yoga-- by practice; yuktena-- being engaged in meditation; cetasa-- by the mind and intelligence; na anya-gamina-- without their being deviated; paramam-- the Supreme; purusam-- Personality of Godhead; divyam-- transcendental; yati-- one achieves; partha-- O son of Pritha; anucintayan-- constantly thinking of.
He who meditates on Me as the Supreme Personality of Godhead, his mind constantly engaged in remembering Me, undeviated from the path, he, O Partha, is sure to reach Me.
In this verse Lord Krishna stresses the importance of remembering Him. One's memory of Krishna is revived by chanting the maha-mantra, Hare Krishna. By this practice of chanting and hearing the sound vibration of the Supreme Lord, one's ear, tongue and mind are engaged. This mystic meditation is very easy to practice, and it helps one attain the Supreme Lord. Purusam means enjoyer. Although living entities belong to the marginal energy of the Supreme Lord, they are in material contamination. They think themselves enjoyers, but they are not the supreme enjoyer. Here it is clearly stated that the supreme enjoyer is the Supreme Personality of Godhead in His different manifestations and plenary expansions as Narayana, Vasudeva, etc.
The devotee can constantly think of the object of worship, the Supreme Lord, in any of His features -- Narayana, Krishna, Rama, etc. -- by chanting Hare Krishna. This practice will purify him, and at the end of his life, due to his constant chanting, he will be transferred to the kingdom of God. Yoga practice is meditation on the Supersoul within; similarly, by chanting Hare Krishna one fixes his mind always on the Supreme Lord. The mind is fickle, and therefore it is necessary to engage the mind by force to think of Krishna. 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 Krishna, it is certain that at the end of our lives we shall have the same bodily constitution as Krishna.
(Bhagavad-gita As It Is 8.8, Purport)