After a day's work, I heard from my boss today that I am too reserved to talk. If I can't do it again, I'll be fired. What should I do?

You don't like talking. This is your personality. Don't change anything. A leopard cannot change his spots. Even if you want to change it, it is neither fish nor fowl. Besides, you've only heard of it, and you're not sure. If it happens, it means that this job is not suitable for you, and you may find a job that suits you better.

Have confidence in yourself and believe this sentence: I was born to be useful.