The earliest extant systematic account of yoga and a bridge from the earlier Vedic uses of the term is found in the Hindu Katha Upanisad (Ku), a scripture dating from about the third century BCE[…] [I]t describes the hierarchy of mind-body constituents—the senses, mind, intellect, etc.—that comprise the foundational categories of Sāmkhya philosophy, whose metaphysical system grounds the yoga of the Yogasutras, Bhagavad Gita, and other texts and schools (Ku3.10–11; 6.7–8).[101]
According to Zimmer, Yoga philosophy is reckoned to be part of the non-Vedic system, which also includes the Samkhya school of Hindu philosophy, Jainism and Buddhism:[46] "[Jainism] does not derive from Brahman-Aryan sources, but reflects the cosmology and anthropology of a much older pre-Aryan upper class of northeastern India [Bihar] – being rooted in the same subsoil of archaic metaphysical speculation as Yoga, Sankhya, and Buddhism, the other non-Vedic Indian systems."[61][note 6]
The maintenance and promotion of health is achieved through different combination of physical, mental, and social well-being, together sometimes referred to as the "health triangle."[24][25] The WHO's 1986 Ottawa Charter for Health Promotion further stated that health is not just a state, but also "a resource for everyday life, not the objective of living. Health is a positive concept emphasizing social and personal resources, as well as physical capacities."[26]

Many teens suffer from mental health issues in response to the pressures of society and social problems they encounter. Some of the key mental health issues seen in teens are: depression, eating disorders, and drug abuse. There are many ways to prevent these health issues from occurring such as communicating well with a teen suffering from mental health issues. Mental health can be treated and be attentive to teens' behavior.[39]

The great positive impact of public health programs is widely acknowledged. Due in part to the policies and actions developed through public health, the 20th century registered a decrease in the mortality rates for infants and children and a continual increase in life expectancy in most parts of the world. For example, it is estimated that life expectancy has increased for Americans by thirty years since 1900,[55] and worldwide by six years since 1990.[56]

According to Geoffrey Samuel, our "best evidence to date" suggests that yogic practices "developed in the same ascetic circles as the early śramaṇa movements (Buddhists, Jainas and Ajivikas), probably in around the sixth and fifth centuries BCE." This occurred during what is called the ‘Second Urbanisation’ period.[9] According to Mallinson and Singleton, these traditions were the first to use psychophysical techniques, mainly known as dhyana and tapas. but later described as yoga, to strive for the goal of liberation (moksha, nirvana) from samsara (the round of rebirth).[78]
During the period between the Mauryan and the Gupta eras (c. 200 BCE–500 CE) the Indic traditions of Hinduism, Buddhism and Jainism were taking form and coherent systems of yoga began to emerge.[50] This period witnessed many new texts from these traditions discussing and systematically compiling yoga methods and practices. Some key works of this era include the Yoga Sūtras of Patañjali, the Yoga-Yājñavalkya, the Yogācārabhūmi-Śāstra and the Visuddhimagga.

Unintentional weight loss may result from loss of body fats, loss of body fluids, muscle atrophy, or even a combination of these.[25][26] It is generally regarded as a medical problem when at least 10% of a person's body weight has been lost in six months[25][27] or 5% in the last month.[28] Another criterion used for assessing weight that is too low is the body mass index (BMI).[29] However, even lesser amounts of weight loss can be a cause for serious concern in a frail elderly person.[30]
As chronic obstructive pulmonary disease (COPD) advances, about 35% of patients experience severe weight loss called pulmonary cachexia, including diminished muscle mass.[31] Around 25% experience moderate to severe weight loss, and most others have some weight loss.[31] Greater weight loss is associated with poorer prognosis.[31] Theories about contributing factors include appetite loss related to reduced activity, additional energy required for breathing, and the difficulty of eating with dyspnea (labored breathing).[31]
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:
Later developments in the various Buddhist traditions led to new innovations in yogic practices. The Theravada school, while remaining relatively conservative, still developed new ideas on meditation and yogic phenomenology in their later works, the most influential of which is the Visuddhimagga. The Indic meditation teachings of Mahayana Buddhism can be seen in influential texts like the Yogācārabhūmi-Śāstra (compiled c. 4th century). Mahayana meditation practices also developed and adopted new yogic methods, such as the use of mantra and dharani, pure land practices which aimed at rebirth in a pure land or buddhafield, and visualization methods. Chinese Buddhism developed its own methods, such as the Chan practice of Koan introspection and Hua Tou. Likewise, Tantric Buddhism (also Mantrayana, Vajrayana) developed and adopted tantric methods, which remain the basis of the Tibetan Buddhist yogic systems, including the Six yogas of Naropa, Kalacakra, Mahamudra and Dzogchen.[248]
Cancer, a very common and sometimes fatal cause of unexplained (idiopathic) weight loss. About one-third of unintentional weight loss cases are secondary to malignancy. Cancers to suspect in patients with unexplained weight loss include gastrointestinal, prostate, hepatobiliary (hepatocellular carcinoma, pancreatic cancer), ovarian, hematologic or lung malignancies.
Mental illness is described as 'the spectrum of cognitive, emotional, and behavioral conditions that interfere with social and emotional well-being and the lives and productivity of people. Having a mental illness can seriously impair, temporarily or permanently, the mental functioning of a person. Other terms include: 'mental health problem', 'illness', 'disorder', 'dysfunction'.[37]
The Bhagavad Gita ('Song of the Lord') is part of the Mahabharata and also contains extensive teachings on Yoga. According to According to Mallinson and Singleton, the Gita "seeks to appropriate yoga from the renunciate milieu in which it originated, teaching that it is compatible with worldly activity carried out according to one's caste and life stage; it is only the fruits of one's actions that are to be renounced."[109] In addition to an entire chapter (ch. 6) dedicated to traditional yoga practice, including meditation,[113] it introduces three prominent types of yoga:[114]
Systematic activities to prevent or cure health problems and promote good health in humans are undertaken by health care providers. Applications with regard to animal health are covered by the veterinary sciences. The term "healthy" is also widely used in the context of many types of non-living organizations and their impacts for the benefit of humans, such as in the sense of healthy communities, healthy cities or healthy environments. In addition to health care interventions and a person's surroundings, a number of other factors are known to influence the health status of individuals, including their background, lifestyle, and economic, social conditions and spirituality; these are referred to as "determinants of health." Studies have shown that high levels of stress can affect human health.[15]
Focusing more on lifestyle issues and their relationships with functional health, data from the Alameda County Study suggested that people can improve their health via exercise, enough sleep, maintaining a healthy body weight, limiting alcohol use, and avoiding smoking.[27] Health and illness can co-exist, as even people with multiple chronic diseases or terminal illnesses can consider themselves healthy.[28]
Yoga may have pre-Vedic elements.[45][46] Some state yoga originated in the Indus Valley Civilization.[51] Marshall,[52] Eliade[10] and other scholars note that the Pashupati seal discovered in an Indus Valley Civilization site depicts a figure in a position resembling an asana used for meditation, Mulabandhasana. This interpretation is considered speculative and uncertain by more recent analysis of Srinivasan[10] and may be a case of projecting "later practices into archeological findings".[53]
These meditations were seen as being supported by the other elements of the eightfold path, such as the practice of ethics, right exertion, sense restraint and right view.[244] Two mental qualities are said to be indispensable for yogic practice in Buddhism, samatha (calm, stability) and vipassanā (insight, clear seeing).[245] Samatha is the quality of a stable, relaxed and calm mind. It is also associated with samadhi (mental unification, focus) and dhyana (a state of meditative absorption). Vipassanā meanwhile, is a kind of insight or penetrative understanding into the true nature of phenomena. It is also defined as "seeing things as they truly are" (yathābhūtaṃ darśanam). The true nature of things is defined and explained in different ways, but an important and unique feature of classical Buddhism is its understanding of all phenomena (dhammas) as being empty of a self (atman) or inherent essence, a doctrine termed Anatta ("not-self") and Śūnyatā (emptiness).[246][247] This is in sharp contrast with most other Indian traditions, whose goals are founded either on the idea of an individual soul (atman, jiva, purusha) or a universal monistic consciousness ( Brahman). Vipassanā also requires an understanding of suffering or dukkha (and thus the four noble truths), impermanence (anicca) and interdependent origination.