I’m spineless and ashamed of it. How do I grow a backbone?

So ashamed of it that I’m using a burner account and altering details lest this be traced back to me. I’m a woman in my early 30s. I have a fairly normal life, close knit family, good friends. I consider myself to be a very empathetic person, with a soft spot for animals and other helpless beings (children, elderly, etc). I don’t think I’m a bad person, but do have plenty of character flaws. There is one I’ve started becoming more and more conscious of as I mature. I’m a very non confrontational person, probably due to social anxiety. I have a very difficult time speaking up, for myself and for others. This makes me feel terrible about myself. And I greatly envy those who speak out passionately about their beliefs. I envy those who openly defend others in public. Or speak up when they’ve been wronged. I want to be that person so badly but I have a terrible fear of being seen/judged. And this holds me back. I WANT to be courageous. I want to be the first to speak up loudly in defense of another. I want to be able to stop my car in the middle of traffic to help a family of ducks cross the road. I want to confidently and without hesitation call out someone who has insulted me. But I’m terrified. Terrified to be wrong. Terrified to be seen or heard. Terrified to be confronted and unable to defend myself, and thus humiliated in front of others. When I read about things like the bystander effect, I know immediately that I’d be a bystander. And that makes me feel ashamed to know this about myself. I want to change and don’t know where to begin, or if this is even something I can change. Maybe this is just my nature and I’m doomed to be a spineless voiceless human who contributes nothing to society. I know I’m being harsh, judging myself harshly. But I feel like society also judges those like me. I see it all the time, in the comments sections of videos and news stories that show incidents where people did not step up to help. I see how harshly people like this are condemned. And then I’m consumed by guilt knowing that I’d be among those who stood by and did nothing to help. I welcome any advice or words of support, or stories from those who were once like me and managed to change 🖤