Classical yoga incorporates epistemology, metaphysics, ethical practices, systematic exercises and self-development techniques for body, mind and spirit. 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. This is done by stilling one's thought waves (citta vritti) and resting in pure awareness of puruṣa.
a technique for entering into other bodies, generating multiple bodies, and the attainment of other supernatural accomplishments; these are, states White, described in Tantric literature of Hinduism and Buddhism, as well as the Buddhist Sāmaññaphalasutta; James Mallinson, however, disagrees and suggests that such fringe practices are far removed from the mainstream Yoga's goal as meditation-driven means to liberation in Indian religions.
The Yoga Yajnavalkya is a classical treatise on yoga attributed to the Vedic sage Yajnavalkya. It takes the form of a dialogue between Yajnavalkya and Gargi, a renowned philosopher. The text contains 12 chapters and its origin has been traced to the period between the second century BCE and fourth century CE. Many yoga texts like the Hatha Yoga Pradipika, the Yoga Kundalini and the Yoga Tattva Upanishads have borrowed verses from or make frequent references to the Yoga Yajnavalkya. The Yoga Yajnavalkya discusses eight yoga Asanas – Swastika, Gomukha, Padma, Vira, Simha, Bhadra, Mukta and Mayura, numerous breathing exercises for body cleansing, and meditation.
One of the earliest and most influential sub-traditions of Vedanta, is Advaita Vedanta, which posits nondualistic monism. This tradition emphasizes Jñāna yoga (yoga of knowledge), which is aimed at realizing the identity of one's atman (soul, individual consciousness) with Brahman (the Absolute consciousness). The most influential thinker of this school is Adi Shankara (8th century), who wrote various commentaries and original works which teach Jñāna yoga. In Advaita Vedanta, Jñāna is attained on the basis of scripture (sruti) and one's guru and through a process of listening (sravana) to teachings, thinking and reflecting on them (manana) and finally meditating on these teachings (nididhyāsana) in order to realize their truth. It is also important to develop qualities such as discrimination (viveka), renunciation (virāga), tranquility, temperance, dispassion, endurance, faith, attention and a longing for knowledge and freedom ('mumukṣutva).' Yoga in Advaita is ultimately a "meditative exercise of withdrawal from the particular and identification with the universal, leading to contemplation of oneself as the most universal, namely, Consciousness".
If you have high blood pressure, diabetes, or heart problems, ask your doctor what you can do. You may need to avoid certain postures, like those in which you're upside down or that demand more balance than you have right now. A very gentle program of yoga, coupled with a light aerobic activity like walking or swimming, may be the best way to start.