My "moment" happened due to a lot of errors on my part. It encouraged me to make sure that I don't find myself in that situation again, and carrying a gun is one part of the overall learning experience.
Late at night. In a city. After about 3 or 4 beers. Took a short cut, off the main drag, through a parking lot. The area is full of panhandlers, and when this guy walked up, I assumed he was just another guy asking for money. He wasn't asking. Afterwards, as he walked away, I realized he had another guy standing in the shadows off to the side. I know... it sounds like a list of what not to do, but that's the sad truth.
Afterwards, I decided to take some steps to make sure I didn't find myself in that situation again. I got my concealed carry permit. I also took a training course. Which made me realize I needed more. I took several more classes and continue to do so. I also have learned a lot from this website and others.
How would I have used my gun in that specific situation? In that situation, if I had a gun and tried to use it, the guy with the gun in my face would have shot me. If I tried to throw down a wallet and distract him, the guy I didn't see till later would have shot me.
The thing I've learned is that situational awareness is the only thing that would have prevented this one. Don't go to that location. Don't have too much to drink and allow it to compromise your safety. Don't allow someone to get that close. Be aware of your surroundings and see him coming first. The list goes on and on. The difference in my life is that now I try to be aware at all times. It's a habit that you really have to work on but it's kind of fun after a while. Instead of feeling paranoid, I feel more relaxed. Hope situational awareness is the only part of the gun training I'll ever need!