Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 28
यं योगिनो योगसमाधिना रहोध्यायन्ति लिङ्गादसतो मुमुक्षया ।तस्यैष दैत्यऋषभ: पदाहतोमुखं प्रपश्यंस्तनुमुत्ससर्ज ह ॥ २८ ॥
yaṁ yogino yoga-samādhinā rahodhyāyanti liṅgād asato mumukṣayātasyaiṣa daitya-ṛṣabhaḥ padāhatomukhaṁ prapaśyaṁs tanum utsasarja ha
Brahmā continued: He was struck by a forefoot of the Lord, whom yogīs, seeking freedom from their unreal material bodies, meditate upon in seclusion in mystic trance. While gazing on His countenance, this crest jewel of Diti’s sons has cast off his mortal coil.
The process of yoga is very clearly described in this verse of Śrīmad-Bhāgavatam. It is said here that the ultimate end of the yogīs and mystics who perform meditation is to get rid of this material body. Therefore they meditate in secluded places to attain yogic trance. Yoga has to be performed in a secluded place, not in public or in a demonstration on stage, as nowadays practiced by many so-called yogīs. Real yoga aims at ridding one of the material body. Yoga practice is not intended to keep the body fit and young. Such advertisements of so-called yoga are not approved by any standard method. Particularly mentioned in this verse is the word yam, or “unto whom,” indicating that meditation should be targeted on the Personality of Godhead. Even if one concentrates his mind on the boar form of the Lord, that is also yoga. As confirmed in Bhagavad-gītā, one who concentrates his mind constantly in meditation upon the Personality of Godhead in one of His many varieties of forms is the first-class yogī, and he can very easily attain trance simply by meditating upon the form of the Lord. If one is able to continue such meditation on the Lord’s form at the time of one’s death, one is liberated from this mortal body and is transferred to the kingdom of God. This opportunity was given to the demon by the Lord, and therefore Brahmā and other demigods were astonished. In other words, the perfection of yoga practice can be attained by a demon also if he is simply kicked by the Lord.