I was a town kid and never took any sort of life apart from insects until I suppose my late 30's. Oh, and that one skunk I ran over as a teenager. Unpleasant for all involved, I must say, though I suspect the skunk did get the worst of it. First thing I can recall deliberately killing was a squirrel. My oldest son developed an interest in hunting, which I'd never done, but I brought him out squirrel hunting on game lands several times and never saw a single squirrel. Finally one showed up and my son was unable for some reason to take a shot, so I shot it. I can't say it felt very monumental. I did not ask myself, before the shot, if I would have a hard time taking the shot. I was out squirrel hunting, so when I got a good shot at a squirrel, I took it. Seemed pretty straightforward to me. Delicious meat, too.
Later, when we moved to the country and got a little land, I took up deer hunting. My very first time out in the woods after deer, first time ever, I saw a deer walking directly towards me. I thought for a moment and decided not to shoot the deer. I couldn't tell for sure, but I thought it looked awfully small. It certainly had no antlers. It's perfectly legal to shoot antlerless deer where I hunt, and many hunters love to take the little ones because the meat is so tender. But I simply made the judgment that I did not want my first deer to be this little creature, and although I took the trouble to get my gun up and on the deer (to test my capability to actually do that work without the deer seeing me), I did not shoot. I did not ask myself, afterwards, if there was some deep resistance to shooting pretty little deer. I knew I had been out deer hunting and had made a judgment call about not shooting the deer--and I knew that I could make a different judgment call when a different deer showed up. I did not get an opportunity that fall, but on opening day of muzzle loader season the next year, a 4 pointer walked up on me and I shot him with no trouble. I've shot quite a few since. Never found myself struggling with the decision to shoot.
We've been raising meat chickens for the last 5 years or so. I put them in a cone and cut their carotids. (Or whatever they're called on a chicken.) It's not a day I look forward to, but killing the birds is just something that has to get done so we can eat decent meat at a price we can afford. It has never caused me any difficulties. We raise the birds to eat them, and to eat them, we prefer to kill them and cook them. So it's got to get done.
I've carried a pistol for quite awhile now, and never used it in a defensive situation, except once. A group of 3 dogs came into my back yard, and I yelled at them to go. One of them charged me. I drew my gun. Fortunately, the dog decided that I was not going to be intimidated, and he and the others left. I am a dog lover and I absolutely have no desire to harm any dog, but if that dog had taken about two more steps he'd have been shot. I did not shoot because I did not have to, but if I'd had to, I would have shot that dog and slept fine that night.
If some human being decides to put me in a position where I am in imminent and otherwise unavoidable danger of death or grave bodily harm, or someone I love is, I will shoot that person until he stops doing what he's doing. I'm a Christian and commanded to love my enemy, but I'm not expected to let him kill me or my loved ones. I don't want to hurt anyone, but if they choose to force my hand, I will respond as needed.
There are always questions that the outsider can ask--I mean, the outsider to my psyche--about how I could know how I'll react in such a situation. How do I know I'll be able to pull the trigger if I have to? Can I be sure? The answer to that is, yes, I am sure and I don't need to actually go through the situation to find out how I'll react. I've already decided how I'll react, and I won't fail in that resolve. Obviously I don't speak from experience and that makes my testimony of dubious value to others, unlike some of what our LEO or military members have to offer, but I do think it's important to take into account that you can and should have every confidence in your own firmness of conviction and the reliability of your decisionmaking in shaping your actions.
And though this might seem a bit of an anticlimax in some ways, it is helpful to me to know that I have ACLDN so that at least some of the potential practical problems that might follow on such an action can be forestalled.