Yoga is a process of moving from the gross to the subtle. From the manifest, backwards to the unmanifest where the pure light which dwells within each of us is most bright.
While in the west we have come to see yoga as an exercise regime, or a sequence of postures and movements it is important to stress that this is the first, peripheral aspect of a complete way of life. The postures are of course crucial as they are the gateway to new realms of consciousness and brighter cleaner ways of understanding the world we live in and by extention, ourselves. The body is needed to experience this and must first be prepped, or made ripe, by breaking down the physical obstructions we have created for ourselves over years of mechanical response systems. As we break down the physical structure this, in turn, will be slowly but surely reforming our thought processes, and gently tapping away at blockages, not only physical but psycho & emotional also. Physical and mental health are positive bi products of yoga. Healthy living is not something which ever needs to be imposed but happens over time organically through a regular yoga practise.
Once the threads of the body become loosened by the physical efforts of yoga and the mind becomes ready to access new ideas and thought processes the more internal aspects of yoga will naturally show themselves to you.
If you would like to read more about yoga there are some free texts for you to download on the data page.