Relationships work best when partners are equals (equal power, equal rights, equal responsibilities) but it's not an easy thing for most people to achieve.
I hear ya. Coming fall, I've been in the same relationship for thirty years, and next year we'll (probably

) be celebrating our 25th wedding anniversary. She's an intelligent and educated woman, with a demanding job, and that makes her both strong and opinionated. I won't say I'm under any thumb, though, I've got an education and a job myself, we regard each other as equals and we are both very aware that mutual respect and understanding is vital for a successful long-term relationship. I use to tell kids these days that one of the big secrets of keeping a relationship is to pick your battles carefully. If a thing really doesn't matter that much to you, it's a smart thing to let it pass.
As far as I can remember, my wife has really only vetoed one of my wishes¹, and that was when I wanted to try skydiving. That was more of a wild idea than a deeply rooted wish for me, so I chose to let it pass. In all other issues, if one of us is uncomfortable with the wishes and desires of the other, we discuss as rationally as we can, and we negotiate a compromise that both can live - and live well - with. We've even found common ground for raising three children in a family where one of the parents is religious and the other is an atheist (and, to my great satisfaction, neither of the kids have turned out religious

).
If my wife were to tell me the same thing the OP has experienced, the advice of growing a pair and telling her how it was going to be whether she liked it or not, would be very bad advice. Very, very bad indeed. OTOH, our standard solution of sitting down and discussing the subject calmly, analyzing real risks, respecting each others' feelings and ideas about the issue, and the basis of those feelings and opinions, would most probably lead to a good compromise. I'd respect her anxiety and concern for me and find a way to do "my thing" safely while she'd see that I value her opinion and adjust my way to meet her needs. I'd understand that she's worried for me and loves me, while at the same time I'd get to do what I wanted, albeit not necessarily exactly the way I first assumed I'd do it. IMO, that's how you solve conflicts in a healthy partnership, not by "growing a pair" and telling the other person her how it's gonna be. How is she supposed to continue believing she's the most important person in my life (excepting the children, of course) if I don't respect her concerns?
¹ BTW, she's also told me I'm not allowed to dive overhead environments. That's perfectly fine with me, the thought of overhead diving scares the heebie-jeebies out of me. Since she was ignorant about diving before I took it up, I suspect that some of her opinion on that has its origin in my own attitude towards that kind of diving...