The purpose and philosophy of Yoga is  to bring unison between mind, body and spirit, through specific exercises, breathing and meditation.
Yoga postures (asanas) are excellent for developing and maintaining the flexibility and muscle strength. They also help you to relax. At this physical level yoga contributes a great deal to fitness and well-being.
However, yoga asanas should  not just  work on the physical body but also on the subtle bodies. Because there is a focus on inner awareness of breathing and the internal sensations, as well as the physical positions themselves, this activates the etheric body more strongly than ordinary exercise.

The activation also extends into the emotional and mental bodies.
The aim of the asanas is to align these bodies, helping to restore health wherever in the subtle bodies the originating problem might be