Yoga gurus from India later introduced yoga to the West,[16] following the success of Swami Vivekananda in the late 19th and early 20th century with his adaptation of yoga tradition, excluding asanas.[16] In the 1980s, a very different form of modern yoga, with an increasing number of asanas and few other practices, became popular as a system of exercise across the Western world.[15] Yoga in Indian traditions, however, is more than physical exercise; it has a meditative and spiritual core.[17] One of the six major orthodox schools of Hinduism is also called Yoga, which has its own epistemology and metaphysics, and is closely related to Hindu Samkhya philosophy.[18]
The focus of public health interventions is to prevent and manage diseases, injuries and other health conditions through surveillance of cases and the promotion of healthy behavior, communities, and (in aspects relevant to human health) environments. Its aim is to prevent health problems from happening or re-occurring by implementing educational programs, developing policies, administering services and conducting research.[53] In many cases, treating a disease or controlling a pathogen can be vital to preventing it in others, such as during an outbreak. Vaccination programs and distribution of condoms to prevent the spread of communicable diseases are examples of common preventive public health measures, as are educational campaigns to promote vaccination and the use of condoms (including overcoming resistance to such).
Niyama (The five "observances"): Śauca (purity, clearness of mind, speech and body),[152] Santosha (contentment, acceptance of others and of one's circumstances),[153] Tapas (persistent meditation, perseverance, austerity),[154] Svādhyāya (study of self, self-reflection, study of Vedas),[155] and Ishvara-Pranidhana (contemplation of God/Supreme Being/True Self).[153]

The first known appearance of the word "yoga", with the same meaning as the modern term, is in the Katha Upanishad,[10][95] probably composed between the fifth and third century BCE,[96][97] where it is defined as the steady control of the senses, which along with cessation of mental activity, leading to a supreme state.[67][note 13] Katha Upanishad integrates the monism of early Upanishads with concepts of samkhya and yoga. It defines various levels of existence according to their proximity to the innermost being Ātman. Yoga is therefore seen as a process of interiorization or ascent of consciousness.[99][100] It is the earliest literary work that highlights the fundamentals of yoga. White states:

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.
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]
In recent years, the related areas of fitness and figure competition have increased in popularity, surpassing that of female bodybuilding, and have provided an alternative for women who choose not to develop the level of muscularity necessary for bodybuilding. McLish would closely resemble what is thought of today as a fitness and figure competitor, instead of what is now considered a female bodybuilder. Fitness competitions also have a gymnastic element to them. A study by the Clinical Journal of Sport Medicine found that female bodybuilders who are taking anabolic steroids are more likely to have qualified for substance dependence disorder, to have been diagnosed with a psychiatric illness, or to have a history of sexual abuse.[14]
As the number of service sector jobs has risen in developed countries, more and more jobs have become sedentary, presenting a different array of health problems than those associated with manufacturing and the primary sector. Contemporary problems, such as the growing rate of obesity and issues relating to stress and overwork in many countries, have further complicated the interaction between work and health.

Just as there was a shift from viewing disease as a state to thinking of it as a process, the same shift happened in definitions of health. Again, the WHO played a leading role when it fostered the development of the health promotion movement in the 1980s. This brought in a new conception of health, not as a state, but in dynamic terms of resiliency, in other words, as "a resource for living". 1984 WHO revised the definition of health defined it as "the extent to which an individual or group is able to realize aspirations and satisfy needs and to change or cope with the environment. Health is a resource for everyday life, not the objective of living; it is a positive concept, emphasizing social and personal resources, as well as physical capacities".[10] Thus, health referred to the ability to maintain homeostasis and recover from insults. Mental, intellectual, emotional and social health referred to a person's ability to handle stress, to acquire skills, to maintain relationships, all of which form resources for resiliency and independent living.[9] This opens up many possibilities for health to be taught, strengthened and learned.
A yoga system that predated the Buddhist school is Jain yoga. But since Jain sources postdate Buddhist ones, it is difficult to distinguish between the nature of the early Jain school and elements derived from other schools.[89] Most of the other contemporary yoga systems alluded in the Upanishads and some Buddhist texts are lost to time.[90][91][note 12]