Shrimad Bhagavad Gita As It Is -Shri Shrimad A.C Bhaktivedanta Swami Prabhupada
Chapter 6: Verse-15
yunjann evam sadätmänam
Thus practicing constant control of the body, mind and activities, the mystic transcendentalist, his mind regulated, attains to the kingdom of God [or the abode of Krsna] by cessation of material existence.
The ultimate goal in practicing yoga is now clearly explained. Yoga practice is not meant for attaining any kind of material facility; it is to enable the cessation of all material existence. One who seeks an improvement in health or aspires after material perfection is no yogi according to Bhagavad-gita. Nor does cessation of material existence entail one’s entering into “the void,” which is only a myth. There is no void anywhere within the creation of the Lord. Rather, the cessation of material existence enables one to enter into the spiritual sky, the abode of the Lord. The abode of the Lord is also clearly described in the Bhagavad-gita as that place where there is no need of sun, moon or electricity. All the planets in the spiritual kingdom are self-illuminated like the sun in the material sky. The kingdom of God is everywhere, but the spiritual sky and the planets thereof are called param dhäma, or superior abodes. A consummate yogi, who is perfect in understanding Lord Krsna, as is clearly stated herein by the Lord Himself (mat-cittah, mat-parah, mat-sthänam), can attain real peace and can ultimately reach His supreme abode, Krsnaloka, known as Goloka Vrndävana. In the Brahma-samhitä  it is clearly stated, goloka eva nivasaty akhilätma-bhütah: the Lord, although residing always in His abode called Goloka, is the all-pervading Brahman and the localized Paramätmä as well by dint of His superior spiritual energies. No one can reach the spiritual sky (Vaikuetha) or enter into the Lord’s eternal abode (Goloka Vrndävana) without the proper understanding ofkrsnaand His plenary expansion Visnu. Therefore a person working in krsna consciousness is the perfect yogi, because his mind is always absorbed in Krsna’s activities (sa vai manah krsna-pädäravindayoh). In the Vedas alsowe learn, tam eva viditväti mrtyum eti: “One can overcome the path of birth and death only by understanding the Supreme Personality of Godhead, Krsna.” In other words, perfection of the yoga system is the attainment of freedom from material existence and not some magical jugglery or gymnastic feats to befool innocent people.
- yunjan=practicing; evam=as mentioned above; sadä=constantly;
ätmänam=body, mind and soul; yogi=the mystic transcendentalist; niyata-mänasah=with a regulated mind; säntim=peace; nirväna-paramäm=cessation of material existence; mat-samsthäm=the spiritual sky (the kingdom of God); adhigacchati=does attain.
- Svetäsvatara Upanisad 3.8