In your opinion what is the most important factor that affects proficiency in learning a second language?

In your opinion what is the most important factor that affects proficiency in learning a second language?

In my opinion, the most important factor that affects proficiency in learning a second language is the confidence. To begain with, I think if a pearon without the confidence , he or she cann't do anything. For learning a second language, people should be able to speak with confident. Speaking with confident is the best way to improve their second language.Therefore, the ability of confidence for learning a second language is very important.
Morover, not only the confidence could affects the proficiency improvement of speaking in second language, but also it affects on the process of learing writing, reading and listening. For some people, they have confidence to make mistakes for the process of learning. Those people have more quickly progress than others who are lack of confidence.If people are afraid of making mistakes, they cannot make any progress.
In conclusion, in order to be a successful person in learning a second language, he or she should have the confidence to learn it.