"Teach what is inside of you, not as it applies to you, to yourself, but as it applies to the other."
Professor T. Krishnamacharya
Yoga is a state of perfect serenity, combined with perfect lucidity. The same name is used for a set of techniques, including physical positions or movements, certain forms of breathing, concentration and meditation, which are done with the aim of helping the person to approach this state of yoga.
Everyone is different from each other. Each person is unique. What is good for someone may not be good for someone else. Yoga techniques are powerful, they are excellent! We take the most advantage of them when they are adapted to each person, at that moment.
When transmitting yoga we should take in consideration who we are working with. What we offer should be built carefully for that person (it should not be applied to someone else, because the other person will be different) and should not be always the same work, because the person changes in time, changes with the seasons, with the activity.
This careful application of the Yoga techniques is called Viniyoga and it was recommended by Shri Krishnamacharya and his son TKV Desikachar. Several Occidental teachers applied it to their teachings.