Hehe, I find this topic intriguing as hell.
I've been taught several ways of achieving this. But, no tthat long ago I learned a meditative practice Ninjutsu practitioners call "the demon." I think this was one of the most influential things I've ever learned.
You have to have experience meditating before you can do this. If you can't enter a relatively deep meditative state then this can't happen.
Basically this theory is based around the creation of a creature that embodies all the desired attributes needed for combat. You must first visualize this creature(demon) and build it to your exact specifications. Your demon may have the following attributes...
Fearlessness
amazing speed
ruthlessness
focus
ability to not feel pain
incredible strength
An intimidating look that would scare the shit out of anyone
etc etc etc
You must visualize this demon utilizing these traits flawlessly under every imaginable condition. Larger opponents, multiple opponents, opponents with all types of weapons, etc. You must see him clearly excecuting techniques flawlessly with unblievable speed and precision, all the while showing no fear or hesitation. This must be continued for quite a while. I'm talking months and months.
This next part is the hard part.....
You now need to see this demon manifesting itself in you. Imagine yourself becoming one with this demon, to the point where it completely takes over your body and mind, and you become the demon. You are now the one executing flawless combat tactics in the form of this demon. This takes a long time.
The idea here is to create a type of post hypnotic suggestion. Like the hypnotist at a fair. When he says the word dog, some person starts barking loudly. Well, when you encounter a particular combat scenario, or simply feel the rush of fear in a confrontation, that is the trigger equivilant to the word "dog" and SNAP, the demon manifests itself in you providing you with all of the traits of the demon. You react. You have no choice but to react exactly how your demon would, just like the person has no choice but to bark. You don't think about it, it becomes instinctual.
I know this sounds out there, but it is one of the single most importat things I have ever done. It took me quite some time to develop my demon and have it work with me, but it works. Since I really don't fight anymore, I have been able to transfer this into my lifting. I can actually conjur that fucker up and lift insane amounts of weight because he can.
I had a gun pulled on myself and a buddy back east a couple years ago. The instant I saw the gun, my body was between my friend and the assailant, my left hand was going for the throat and my right hand for the weapon. My right hand grabbed the slide at the time of throat impact, hit a joint up and over my shoulder, then threw his coughing gasping body over me, hit an arm bar and had the gun pointed at his friend. At that point I realized that I had reinacted a disarm drill that I had my demon do a thousand times. I can actually remember seeing him do it, not me. It was fucking beaultiful. Only after I left the scene did I get any sort of adrenaline dump.
If you're willing to put in the time meditating and creating this, I promise you that you will be happy with the ability.