Please ensure that you are in constant touch with your trainer even after completion of yoga learning sessions. There are tremendous possibilities that we may have doubts on prolonged practice sessions. Please do ensure that you do not accumulate any of your doubts. Having a good rapport with your trainer helps you in having a better understanding for the things that you do. There are possibilities that you may even forget your doubts after certain time span. So try to clarify your doubts as and when you get time to clarify them. One of my friends has one such experience where in he was doing practices wrongly because of his hesitations to clarify his doubts. The effects of such things would really be adverse. So please be careful and try to do your practices diligently and clarify the doubts as early as possible.