You can start this process by making a detailed list of your accomplishments, how you achieved them, and why you're proud.  For example, you could be proud of graduating from college because you're the first person in your family to do so, and you did it while working two jobs. This will help you see that you truly have achieved things, and it will give you deeper insight into your accomplishment. Many of us are kinder and quicker to give out praise to others than ourselves.  To help you be more objective and overcome any reluctance you might have to praise yourself, think about your skills and achievements from an outside perspective. You can do this by writing down positive things about yourself in the third person, as though you were writing a letter of recommendation or endorsement about a friend or coworker. Arrogant, self-centered people (and people who are insecure) tend to go on and on about themselves and their exploits, even when the people they're talking to have stopped listening.  Learn to spot body language cues like glazed eyes, glancing at the watch, or picking at fluff on clothing. These cues can show you that you're getting tiresome and you need to stop bragging. Stop talking about yourself and ask the other person about himself or herself. Aim to listen and to give summary feedback that reveals that you understand what the listener has said. For example, "What I hear you saying is..." Doing so is both a compliment to them and an excellent reflection on your character. Listening will always impress people, especially when you make it clear you understand. Be concise. If you can get your idea across in a 1 or 2 sentence statement, what you say is more likely to stick in people's minds. If you ramble on about yourself for 15 minutes, then people are going to run away from you the next time they see you coming down the hall because they'll think you're arrogant and annoying. At the same time that you acknowledge your accomplishments, do not ignore areas you want to improve. Ignoring your...

TL;DR in Vietnamese:
Xây dựng lòng tự tin đích thực bằng cách nhận biết những phẩm chất tốt đẹp của bạn. Tránh việc chỉ toàn nói về mình. Đặt mục tiêu hoàn thiện bản thân. Nhấn mạnh các kỹ năng của mình nếu bạn là phụ nữ. Nhờ sự giúp đỡ nếu cần thiết. Trao tặng mọi người những lời khen chân thành.