Yoga is a practical aid, not a religion. Yoga is an ancient art based on a harmonizing system of development for the body, mind, and spirit. The continued practice of yoga will lead you to a sense of peace and well-being, and also a feeling of being at one with their environment. This is a simple definition.Think of this practice as being the means and tools to realign and rebalance your vehicle (body) on a regular basis. You take control and you can then become your body mechanic instead of having to pay someone else to do it (medical professionals). Because your body is finely tuned you will find that your chances for injuries and illnesses will drop as you are in a much more attuned state. 
If you are doing yoga everyday then your body is fit and fine. You have proper oxygen in your body then your active ness better. You are need doing yoga. Then I am sure you are living better help. 
This topic is help of yoga.org.