Little experience from a few months ago.
Somebody cut me in line at an atm. After calling him out on it he starts talking to me in a highly agressive manner, getting, and literally holding his fist into my face. Multiple death threats coming from him. I simply stand there and respond verbally, his card keeps declining so I start teasing him a lil about it 
At some point I´m tired of him getting all in my space like that and push away his arm. He responds with a throat strike attempt, which I blocked, he shoves me around into a different position.
Comes at me again, I give him a quick kick into the solar plexus, maybe a bit lower I don´t know exactly, but it sure as hell worked. Suddenly he is like paralyzed, staring down at himself for a few seconds.
I ask him if he still wants to keep going but he seems unable to talk and just turns around.
He was at least a head taller and around 20kg heavier than me, at that time I haven´t trained combat for years, just on my way to my first Muay Thai lesson, had Spartan in my stack for around 3 months I think?
I felt the adrenaline rush, yet comfortable during the whole encounter. Subconsciously I knew exactly to which point he´d just try to intimidate/puff his chest out, and when he´d actually attack, and also that I am 100% capable of neutralizing him if necessary.
I have never experienced myself moving with such speed, accuracy and precision, the block and kick felt completely natural and perfect in its execution, like having the muscle memory of an experienced fighter. When I got home I realized that he actually tried to kill me and got lucky, others would´ve finished him right there.
This experience definetly reinforced alot of self assuredness.
I won´t start anything, but rest assured I can finish it if necessary.