Alexander Wynne observes that formless meditation and elemental meditation might have originated in the Upanishadic tradition.[93] The earliest reference to meditation is in the Brihadaranyaka Upanishad, one of the oldest Upanishads.[67] Chandogya Upanishad describes the five kinds of vital energies (prana). Concepts used later in many yoga traditions such as internal sound and veins (nadis) are also described in the Upanishad.[59] Taittiriya Upanishad defines yoga as the mastery of body and senses.[94]
Various yogic groups had become prominent in Punjab in the 15th and 16th century, when Sikhism was in its nascent stage. Compositions of Guru Nanak, the founder of Sikhism, describe many dialogues he had with Jogis, a Hindu community which practiced yoga. Guru Nanak rejected the austerities, rites and rituals connected with Hatha Yoga. He propounded the path of Sahaja yoga or Nama yoga (meditation on the name) instead.[201] The Guru Granth Sahib states:

Serious eye problems, which include any sudden decrease in vision, with or without eye pain and redness or a blockage of fluid in the eye causing increased pressure in the eye (secondary angle closure glaucoma). These problems can lead to permanent vision loss if not treated. Tell your healthcare provider right away if you have any new eye symptoms.

Alexander the Great reached India in the 4th century BCE. Along with his army, he took Greek academics with him who later wrote memoirs about geography, people and customs they saw. One of Alexander's companion was Onesicritus, quoted in Book 15, Sections 63–65 by Strabo, who describes yogins of India.[107] Onesicritus claims those Indian yogins (Mandanis ) practiced aloofness and "different postures – standing or sitting or lying naked – and motionless".[108]
The environment is often cited as an important factor influencing the health status of individuals. This includes characteristics of the natural environment, the built environment and the social environment. Factors such as clean water and air, adequate housing, and safe communities and roads all have been found to contribute to good health, especially to the health of infants and children.[18][29] Some studies have shown that a lack of neighborhood recreational spaces including natural environment leads to lower levels of personal satisfaction and higher levels of obesity, linked to lower overall health and well being.[30] This suggests that the positive health benefits of natural space in urban neighborhoods should be taken into account in public policy and land use.
Lifestyle choices are contributing factors to poor health in many cases. These include smoking cigarettes, and can also include a poor diet, whether it is overeating or an overly constrictive diet. Inactivity can also contribute to health issues and also a lack of sleep, excessive alcohol consumption, and neglect of oral hygiene (Moffett2013).There are also genetic disorders that are inherited by the person and can vary in how much they affect the person and when they surface (Moffett, 2013).
Various yogic groups had become prominent in Punjab in the 15th and 16th century, when Sikhism was in its nascent stage. Compositions of Guru Nanak, the founder of Sikhism, describe many dialogues he had with Jogis, a Hindu community which practiced yoga. Guru Nanak rejected the austerities, rites and rituals connected with Hatha Yoga. He propounded the path of Sahaja yoga or Nama yoga (meditation on the name) instead.[201] The Guru Granth Sahib states:
The early practice of Jain yoga seems to have been divided into several types, including meditation (dhyāna), abandonment of the body (kāyotsarga), contemplation (anuprekṣā), and reflection (bhāvanā).[253] Some of the earliest sources for Jain yoga are the Uttarādhyayana-sūtra, the Āvaśyaka-sūtra, the Sthananga Sutra (c. 2nd century BCE). Later works include Kundakunda's Vārassa-aṇuvekkhā (“Twelve Contemplations”, c. 1st century BCE to 1st century CE), Haribhadra's Yogadṛṣṭisamuccya (8th century) and the Yogaśāstra of Hemachandra (12th century). Later forms of Jain yoga adopted Hindu influences, such as ideas from Patanjali's yoga and later Tantric yoga (in the works of Haribhadra and Hemachandra respectively). The Jains also developed a progressive path to liberation through yogic praxis, outlining several levels of virtue called gunasthanas.
According to Georg Feuerstein, Laya yoga (yoga of dissolution or merging) "makes meditative absorption (laya) its focus. The laya-yogin seeks to transcend all memory traces and sensory experiences by dissolving the microcosm, the mind, in the transcendental Self-Consciousness."[276] There are various forms and techniques of Laya yoga, including listening to the "inner sound" (nada), practicing various mudras like Khechari mudra and Shambhavi mudra as well as techniques meant to awaken a spiritual energy in the body (kundalini).[277]

Classical yoga incorporates epistemology, metaphysics, ethical practices, systematic exercises and self-development techniques for body, mind and spirit.[144] Its epistemology (pramana) and metaphysics is similar to that of the Sāṅkhya school. The metaphysics of Classical Yoga, like Sāṅkhya, is mainly dualistic, positing that there are two distinct realities. These are prakriti (nature), which is the eternal and active unconscious source of the material world and is composed of three gunas, and the puruṣas (persons), the plural consciousnesses which are the intelligent principles of the world, and are multiple, inactive and eternal witnesses. Each person has a individual puruṣa, which is their true self, the witness and the enjoyer, and that which is liberated. This metaphysical system holds that puruṣas undergo cycles of reincarnation through its interaction and identification with prakirti. Liberation, the goal of this system, results from the isolation (kaivalya) of puruṣa from prakirti, and is achieved through a meditation which detaches oneself from the different forms (tattvas) of prakirti.[240] This is done by stilling one's thought waves (citta vritti) and resting in pure awareness of puruṣa.
Another text which teaches yoga with an Advaita point of view is the Yoga-Yājñavalkya.[262] This work contains extensive teachings on ten Yamas (ethical rules) and ten Niyamas (duties), and eight asanas. It also discusses a theory of nadis and prana (vital breath), and follows this with instructions on pranayama (breath control), pratyahara (sense withdrawal), meditation on mantras, meditative visualizations and Kundalini.
Description of an early form of yoga called nirodhayoga (yoga of cessation) is contained in the Mokshadharma section of the 12th chapter (Shanti Parva) of the Mahabharata (third century BCE).[109] Nirodhayoga emphasizes progressive withdrawal from the contents of empirical consciousness such as thoughts, sensations etc. until purusha (Self) is realized. Terms like vichara (subtle reflection), viveka (discrimination) and others which are similar to Patanjali's terminology are mentioned, but not described.[110] There is no uniform goal of yoga mentioned in the Mahabharata. Separation of self from matter, perceiving Brahman everywhere, entering into Brahman etc. are all described as goals of yoga. Samkhya and yoga are conflated together and some verses describe them as being identical.[111] Mokshadharma also describes an early practice of elemental meditation.[112] Mahabharata defines the purpose of yoga as the experience of uniting the individual ātman with the universal Brahman that pervades all things.[111]
^ Jump up to: a b c d e f g h i Payne, C; Wiffen, PJ; Martin, S (18 January 2012). Payne, Cathy (ed.). "Interventions for fatigue and weight loss in adults with advanced progressive illness". The Cochrane Database of Systematic Reviews. 1: CD008427. doi:10.1002/14651858.CD008427.pub2. PMID 22258985. (Retracted, see doi:10.1002/14651858.cd008427.pub3. If this is an intentional citation to a retracted paper, please replace {{Retracted}} with {{Retracted|intentional=yes}}.)
The Rigveda, however, does not describe yoga, and there is little evidence as to what the practices were.[7] Early references to practices that later became part of yoga, are made in Brihadaranyaka Upanishad, the earliest Hindu Upanishad.[67] For example, the practice of pranayama (consciously regulating breath) is mentioned in hymn 1.5.23 of Brihadaranyaka Upanishad (c. 900 BCE), and the practice of pratyahara (concentrating all of one's senses on self) is mentioned in hymn 8.15 of Chandogya Upanishad (c. 800–700 BCE).[68][note 8] The Jaiminiya Upanishad Brahmana teaches mantra repetition and control of the breath.[71]
One of the best known early expressions of Brahmanical Yoga thought is the Yoga Sutras of Patanjali , the original name of which may have been the Pātañjalayogaśāstra-sāṃkhya-pravacana (c. sometime between 325 - 425) which some scholars now believe included both the sutras and a commentary.[129] As the name suggests, the metaphysical basis for this text is the Indian philosophy termed Sāṃkhya. This atheistic school is mentioned in Kauṭilya's Arthashastra as one of the three categories of anviksikis (philosophies) along with Yoga and Cārvāka.[130][131] The two schools have some differences as well. Yoga accepted the conception of "personal god", while Samkhya developed as a rationalist, non-theistic/atheistic system of Hindu philosophy.[132][133][134] Sometimes Patanjali's system is referred to as Seshvara Samkhya in contradistinction to Kapila's Nirivara Samkhya.[135] The parallels between Yoga and Samkhya were so close that Max Müller says that "the two philosophies were in popular parlance distinguished from each other as Samkhya with and Samkhya without a Lord."[136]