What is Yoga? The sanskrit word “yoga” means union. Union with what? With our original Self, God or Supreme Consciousness. Yoga is a spiritual science for achieving Self realisation or full enlightenment. Meditation is the main practice used in yoga for attaining this spiritual union. Yoga is therefore not a set of stretches and breathing exercises as often thought of in the West.
The stretches (asanas) and breathing (Pranayama) are taught in some of the yoga paths like Hatha Yoga, Raja Yoga and Astaunga Yoga. However the original purpose of these were to aid meditation. If the body is sick it is very difficult to meditate, hence the reason for asanas and pranayama. Although how they are taught in most yoga classes are very different to how they are taught as an aid to Self Realisation, their original intention. The spiritual aspect is usually left out of the asanas and pranayama thereby severely reducing their benefits to just physical and lower mental levels. However for many people these physical and mental benefits are all they are wanting, which is fine. But in the case of pranayama, mental problems can occur if not taught properly. So personal instructions and guidance from a competent teacher is important before attempting pranayama. Some asanas can cause physical problem as well if not taught properly. Again a competent teacher is required even if doing them just for their physical benefits.