How do I get out of my own head and feel comfortable in social situations?

For my whole life (M32) ever since I can remember back, I've been awful at talking to people. Any conversation I enter I'm just met with an overwhelming state of fear and it just won't go away. But I've now hit a point in my life where I want to change it, and really do something about it as it's holding me back in both my professional life and personal life too. I understand the psychology behind it. As a kid I was brought up to be polite, speak only when you're spoken to, if you've got nothing nice to say then don't say anything, respect your elders, and as a result I feel like I got a negative superiority complex where I saw everyone around me as a more respectful figure, so I should just zip it unless I'm adding something constructive to the conversation. I want to be in a position where I can speak my mind freely without fear of judgement. I envy people that can just talk nonsense freely without a care in the world. And yet nothing I've done to date has got me anywhere close to that goal. Is this just my life now?