Li, there is a man called Derren Brown who is a master of NLP and he was able to modify a woman’s beliefs at will with one simple exercise.
You need to imagine the feeling you get when you know you can do something, like when you are sure that you will catch a pass in football, or sure that you’ll pass a test, and attach that feeling to what you are trying to do. For example, I combine the feeling I get before winning a game of Abalone with Lucid Dreaming. Difficult to explain, but very simple in practice. Here’s the Link: