Jehovah's Witnesses are discouraged from yoga, being told that it opens a person to demon attacks and is a form of Hindu worship.
Watchtower 2002 Aug 1 pp.20-22 Yoga Just an Exercise or Something More?
"Whatever health instructors may say to the contrary, yoga does not stop with physical exercises. The book Hindu Manners, Customs and Ceremonies relates the experiences of two yoga novitiates who were under the guidance of a guru. One is quoted as saying: "I made superhuman efforts to hold my breath as long as possible, and only breathed when I was on the point of fainting. . . . One day, at high noon, I thought I saw a bright moon, which seemed to move and sway from side to side. Another time I imagined myself enveloped in thick darkness at midday. My director . . . was greatly pleased when I mentioned these visions to him. . . . The time was not far distant, he assured me, when I should experience much more surprising results from my penance." The second man relates: "He obliged me to stare at the sky every day without blinking my eyes or changing my position. . . . Sometimes I thought I saw sparks of fire in the air; at others I seemed to see fiery globes and other meteors. My teacher was much pleased with the success of my efforts."
The strange sights were evidently what the gurus felt were proper results along the way to the true aim of yogic exercises. Yes, the ultimate goal of yoga is moksha, explained as the merging with some impersonal great spirit. It is described as "the (intentional) stopping of the spontaneous activity of the mind stuff." This is clearly contrary to the goal set out for Christians, who are given the admonition: "Present your bodies a sacrifice living, holy, acceptable to God, a sacred service with your power of reason. And quit being fashioned after this system of things, but be transformed by making your mind over, that you may prove to yourselves the good and acceptable and perfect will of God."Romans 12:1, 2.
The choice of what physical exercise to pursue is a personal one. Christians, however, would not allow anything be it bodily training, eating, drinking, clothing, entertainment, or something else to mar their relationship with Jehovah God. (1 Corinthians 10:31) For those exercising simply for the sake of their health, there are many avenues available that do not involve exposure to the dangers of spiritism and occultism. By keeping clear of practices and beliefs that are rooted in false religion, we may look forward to Gods blessing of a righteous new system of things in which we can enjoy perfect health in body and mind for an eternity."
Watchtower 1983 Jul 15 pp.29-30 Watch Out for This Deceiver!
"But there is a form of exercise that could cause unexpected problems: yoga.
Yoga (a Sanskrit word signifying union of the individual soul with the Supreme Spirit) consists of physical and mental exercises, postures, breathing exercises and intense meditation and concentration. Originating in India, it has been westernized and used to reduce tension, lose weight and gain energy. Books on the market such as Practical Yoga for Businessmen and Yoga for Parents indicate its popularity. Would you practice yoga?
If so, consider this fact: real yoga is not merely a form of exercise. It is a Hindu religious practice. The chief aim of the Yoga philosophy is to teach the means by which the human soul may be completely united with the Supreme Spirit, according to Dr. B. S. Surti. That seems a long way from Yoga for Businessmen, but it is what yoga exercises were originally designed to achieve.
Particularly problematical is yoga-type meditation. Some may point to the fact that the Bible, too, encourages meditation. However, Christian meditation is an active meditation, pondering on upbuilding and beneficial matters. (Psalm 63:6; Proverbs 15:28; Philippians 4:8) Yoga-style meditation is something else. The souls essence, pure intelligence, is obscured by mental activities, whose suppression is the main purpose of Yoga. The mind is to be controlled by constant practice of meditation and nonattachment to material objects. The ultimate result is the suppression of all mental tendencies, conscious or latent.The Encyclopedia Americana.
Is such emptying of the mind healthy? One practicer reports that during one extended period of exercise and meditation, he felt frequent attacks by invisible forces. The demons can take advantage of a mind that is empty and fill it with their own thoughts. (Luke 11:24-26) So beware! This practice could make you their prey."