Importance of Yoga
The popular form of yogic phenomena are more appropriately part of Hatha Yoga. This system involves disciplining the body and mind to gain control over the mind over body and also over nature.
It is considered to be an auxiliary prelude, but not a necessary one, to Raja yoga. The classic texts in Hatha yoga are Hatha (or Hatha-yoga) Pradipika, Gheranda Samhita and Shiva Samhita.
The exercises of yoga to improve bodily and mental strength are more a part of physical and mental culture or health, which of course, is a necessary prelude to the final Kaivalya. However, common people identify yoga with only this part when they refer to it.