I think a lot of how we feel about what people say about us, rest on how we see and feel about ourselves. This means that if someone tells me that I'm dumb and won't succeed, and it keeps bothering me, then I need to take steps to boost my self-esteem.
Here are a few things you could do:
1. Become more self-aware. Know your strengths and weaknesses. Accept yourself, celebrate your abilities, talents, and achievements, and work on improving weak areas. ,
2. Build your self-esteem. Self-esteem is the picture you have of yourself. If your self-esteem is low, start practicing positive self-talk (These are things you tell yourself in your mind again and again). For example, you could start telling yourself, "I have a purpose in life, I'll find it, and achieve it."
3 Know and stick to your values. Since your values are the heart of who you are, stick to them, and don't be influenced by other people's opinions. For example, you respect yourself and respect others, so while some people might say negative things about you, you don't respond in kind.