I typed 'Yoga' into Google search and got the following incredible number of search results ( About 894,000,000 results in 0.69 seconds). The word Yoga comes from a Sanskrit word Yuj, which means to connect. The word Yoga is perhaps the most widely misunderstood term and most of the times people consider that doing some postures, controlled breathing and the body and generally practiced for the physical and mental health. I also heard many other terms like, Hot Yoga , Hip hop Yoga and even came across in Whatsapp,a video of people consuming Beer while doing Yogic postures (God save them).
So going with what most people generally think Yoga is - a Physical exercise and some breathing to have a good health,live longer, flexible body etc. But, exercise part which is generally called as Yoga or Yogic postures (called as Asana) is actually a subset of Astanga Yoga, which involves controlling and channeling the body and mind to the higher by following the Asta angas or eight limbs like, Yama, Niyama,Asana, Pranayama,Pratyahara, Dharana,Dhyana, Samadhi.
The first four limbs—yama, niyama, asana and pranayama—are considered external cleansing practices and involving living in seclusion, controlling the senses, maintaining a posture made of special materials like Kusa grass, deer skin and controlling the breath. Next four- pratyahara, dharana, dhyana and samadhi are considered as the internal cleansing practices which are even more difficult to practice and involve withdrawal of mind from senses, concentration, deep meditation and union with the object of meditation. I am not talking against Yoga that is being practiced today. Totally agree with all the health benefits it gives. In-fact, I myself also practice some of the Yoga Asanas or the postures. What I am getting at is that it cannot quench our spiritual thirst, that experience of non material Happiness and Bliss that someone is ultimately hankering for.
Here is a simple and short video about what is Yoga and what it is not,