People often think Tai Ji seems very difficult. They feel that they make mistakes all the time.
Both of these are true. In Tai Ji, we choose to do things that are difficult. Only when an exercise is difficult enough can it lead to progress. The things we practice in Tai Ji training require a change in ourselves in order to be done properly. Any real change is difficult.
If you try to do something and you become aware of a difference between what you are trying to do and what is actually happening, you can call this difference a mistake. If you try your best to improve while being aware of that difference, you are in a good learning process. Then there are no good reasons to have bad or good feelings about the mistakes. You should never aim for making mistakes, neither should you regret to have tried and failed. Any bad feelings about making a mistake can be used to motivate yourself for improving next time.
Making mistakes can not be avoided. They are always present. Seeing them is the basis of progress.