It depends on what kind of situation we're talking about, as to whether or not I'm likely to stand up for myself. I don't like confrontation, so I'm likely to let most things go by. But I DO notice it when someone, or a business, starts to build up a list of things they are doing or saying, which I should respond to with a strong defense. I pick my battles wisely, I think. What I mean is that if there's somebody who takes advantage of me somehow, and it's a one-time thing, I'll just let it go. But if it happens again and again, sooner or later I'll confront them about all of the those added up, and tell them in a businesslike and matter-of-fact way, that it either will change, or I'll stop having anything to do with that person (or business). To me, it's easier to just let it go than to confront and need to settle every little thing. I'm not saying that's the healthiest way to do it, and I'm aware that there are sometimes negatives to my way of handling these things.
As far as a physical challenge from someone, luckily I haven't been confronted with that much at all. I prefer 100% to talk my way out, and let the other person have the glory of a default win, but if I had to, I'd try my best to physically defend myself. An advantage to being a 200-lb bodybuilder is that most other men won't try anything physical as long as I don't back down and act afraid. A few years ago, we had to fire a woman who was working at our horse ranch, and her boyfriend came with her on the last day to stir up trouble. I was sitting in a chair, and he insulted my wife, and then she started yelling at him to butt out (none of his business). He was a cowboy-type; probably had been drinking, and was average size. All I had to do was stand up and walk toward him, and he backed off. Truth be known; I've never been in a fight in my 46 years of life, and I have no idea how to fight.
Charles