Perhaps if there was a way to disassociate the good exercises of yoga from its spiritual/occult side, that would be a good thing. Unfortunately the two are deeply entwined. For people who are not strong in their faith, yoga can easily lead them away from the One True Church into Eastern spirituality. On its surface, yoga appears benign, and even good for one’s health. In reality, it is sinister and undermines true Catholic spirituality.
In the Vatican document, Jesus Christ the Bearer of the Water of Life - A Christian reflection
on the “New Age”, in sections 2.1 and 126.96.36.199, yoga is called out specifically as being a New Age practice, something not compatible with Catholicism.
Some of the traditions which flow into New Age are: ancient Egyptian occult practices, Cabbalism, early Christian gnosticism, Sufism, the lore of the Druids, Celtic Christianity, mediaeval alchemy, Renaissance hermeticism, Zen Buddhism, Yoga and so on.
Yoga, zen, transcendental meditation and tantric exercises lead to an experience of self-fulfilment or enlightenment.