under the caption Not a Choice for Christians the Watchtower of Aug 1 2002 states on page 22:
"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 God?s blessing of a righteous new system of things in which we can enjoy perfect health in body and mind for an eternity.?2 Peter 3:13; Revelation 21:3, 4."...Yoga?Just an Exercise or Something More?
I would say, matter of choice yes, but a huge no no none the less. Like everything else.
Jahna