Yog or Yoga is an ancient discipline to bring balance (equanimity) of mind and body. 

Yogah Karmasu Kaushalam (Bhagwad Gita 50/2)

Yogaś-Citta-Vr̥tti-Nirodhaḥ (Patanjali Youga Sutra 1.2)

Samatvam Yoga Ucyate (Bhagwad Gita (48/2)

To create and sustain wellness of physical, mental, emotional, and spiritual dimensions. Yoga means union of individual consciousness with the Universal Divine Consciousness by attaining a super-conscious state known Kaivalyam (कैवल्य), a highest state of Samadhi. The oldest book of mankind, Rigveda, mentions about yogic meditation by the wise, Upanishads are replete with yogic concepts, while Patanjali Yoga Sutra is a comprehensive collection Yoga principle and practices. . Bhagavad-Gita dwells on four paths Yogic practices leading to liberation from the cycles of birth and death and union with the Almighty.