It's a tough method to pull off. I can speculate as to how people do it, like being in a psychosis, or being powerfully motivated by emotion, or being backed into a metaphorical corner with no other way out, or perhaps being extraordinarily brave. But the fact of the matter is, hanging is a physical method, and it involves a significant body envelope violation. The lizard part of your brain is going to recognize the danger you're putting yourself in, and it's not gonna let you do it.
I tried to go by hanging for well over a year and a half before I finally admitted to myself that I couldn't do it. I ended up switching to SN, since it's easier to just drink a liquid than intentionally drop your weight into a noose or kick a stool over and hang like a bulb, among other pros for SN. Plus, hanging is quite a brutal method physically. It's quick, sure, but it is very rough on your neck and its machinery. Autopsy reports of the hanged show some pretty heavy damage, and for myself, I couldn't bear to do that to myself.
So please do not beat yourself up over it (I know this probably isn't helpful to hear though). A lot of people try hanging, because it sounds really good on paper. Cheap, accessible, quick. But it's a bit too good to be true. I truly admire those who can actually pull it off.
