Aspirants can build confidence before appearing for the UPSC interview by thorough preparation and practice. Familiarizing themselves with frequently asked questions, current events, and their personal motivations for civil services can enhance their confidence levels. Engaging in mock interviews can simulate real conditions, providing vital experience and constructive feedback. Additionally, positive visualization techniques and affirmations can bolster self-belief. Staying updated and knowledgeable about various topics ensures candidates can engage in discussions fluently, relieving pre-interview anxiety and increasing their confidence to perform well.