How do you actually become a confident person when you know you have potential but can't show it?

I'm 27F, and I've always struggled with low confidence. The frustrating part is that I know I have potential and could excel at certain things, but I constantly doubt myself and hold myself back.

I often see people who seem less capable than me being much more confident, taking opportunities, and ending up in better positions, while I'm still stuck because of my insecurity.

I've tried different ways to become more confident, but it still feels deeply ingrained in me. People even notice it and ask if I'm shy or not confident, which makes me even more self-conscious.

For those who genuinely struggled with low confidence and eventually overcame it...what actually worked for you? How did you become confident enough to believe in yourself and actually show your abilities?