When lifting, competing in any manner etc. you want to “learn” how to have a short-term memory.
What does this exactly mean? It means that learning from your mistakes is good but dwelling on them doesn’t help at all. In some cases, it can impede your progress.
Your confidence is high when you are able to accept the facts that you will make mistakes and not every day in the gym will be your best. Let go of anything that happened prior to that moment. Focus on what you need to do at that precise moment.
When you learn to develop a short-term memory (or just let go of mistakes) you will keep your confidence level high. When you get down on yourself you can lower your confidence level. This can cause you to question yourself, your training, your motives etc. so just let it go remembering growth comes from mistakes. We learn and we grow stronger. Keep your confidence level high!