While practicing tai chi you may find yourself thinking, and my doing it wrong. This is natural. You just need to refocus on your tai chi and try to be in the now. I am reminded of the times my Buddhist friend would come by my home at four in the morning and tap on my window to wake me up for our session of meditation. At the time I was teaching at three schools and working a full-time job at a restaurant. My mind was very full. He told me it was natural for my mind to be full of doubt as I meditated. When that happened I was to refocus on meditation, that was it. He encouraged me that I would be able to focus longer the more I practiced “no mindedness” during our meditation. As soon as I stopped worrying that I was meditating wrong it became easier and I was able to focus. It is natural to feel that your movements are different than your instructors while practicing alone in your backyard. The most important thing is that you are practicing. Even if you are practicing your movement differently than the instructor showed you, it is a lot easier for them to correct you versus teach you the movement again. Because most likely they will be learning a new movement during your next class and having to learn the old movement again plus the new movement you could feel overwhelmed and the urge to quit will enter your mind. So, in summary practice, practice, practice. Right movement or wrong movement both are right.