I have noticed (both in my students and in myself), that when the feeling of being frustrated strikes, it is usually the prelude to some kind of breakthrough! Just when you think you're getting nowhere seems to be the signal that you're about to proceed to a new understanding, or to being able to do something that has been difficult which now becomes easier.

So don't give up to feeling frustrated, but instead regard it as signalling that you're about to advance a step further in your own progress. Frustration is a good sign!

Perserverence in tai chi is much better than natural talent, as talent will only take you so far, but perserverence will see you progress through all the levels, at your own pace. Frustration and the struggle are essential parts of learning, learning both to  achieve and to persevere, which will take you upwards and onwards. Learn to welcome that feeling of frustration as the sign of imminent progress!