Live in peace, fight only when necessary, and when you fight don't fight fair. I have played paintball and airsoft since I was 10 years old, BFD. I can hold my own because I shoot and scoot, and have drilled on how I react for years.
I was also a private security specialist for several years in west baltimore. I have been shot at, I have been hit, and I have shot back as well. Only some of the training that I received prepared me for what I went through. Nothing about what happened to me was tacticool. What it did leave me with was PTSD, bullets in my armor, and rounds expended, and a crap load of grief from the legal system.
You can go through all the wonderfully expensive training in the world, but it is down to the individual and the seriously split millisecond choices you make. I can, will, and have pulled a trigger. My preferance is to never have to do it ever again, but if driven to it, I will. I wish to live in peace, but prepare for a fight.
I suggest that if you want to see how you will react under stress that you do it in airsoft or paintball with milsim (military simulation) players. I have learned a lot in all those years. And in truth the ability to find cover once engaged, return precise fire, and keep moving probably saved my butt. Yes, a game, saved my butt. However, it is up to you to realize once in this make believe environment what will get you dead, and what might actually keep you alive.
You may react the way you are trained, but do not believe that the other guy doesn't know what you are going to do. Oh one more thing, stop watching movies, they are pure BS. And also stop watching youtube, I am a videographer so I only believe 1/100th of any video I see.