Confidence for the UPSC interview can be built through structured preparation, which involves understanding the exam's format and common interview questions. Conducting mock interviews with peers or mentors allows candidates to practice responding effectively. Researching the Service and current affairs related to governance can enhance knowledge and reduce anxiety. Developing strong communication skills through public speaking or group discussions also contributes to a confident demeanor. Lastly, mental conditioning techniques, like visualization, can help aspirants feel more self-assured during the interview.