How would you react in a real life situation?

If someone was charging at me i would do a front kick or a superman punch..

side step and trip

You cannot think only in terms of two men squared off.

You must practice situations: tackles, grabs, sucker punches, chokes from behind,

bear hug from behind, attempted headbutts, knife, gun, and so on.

You tube has an extensive series of voids on situational defense.

You have to prepare for a charge or tackle and have practiced effective, thought-through

defenses in advance. A weakness of many arts is that they only prepare for a fair fight!

the most important thing to do is to remain calm and think as you fight! all combat is chess, forget that and you cease to become a martial artist. if your opponent is dumb enough to just charge you, in my opinion the best thing to do would be to just stand back, and send a well timed back kick straight to his solar plexus, sternum, neck, or head. trust me, back kick is the most powerful strike there is. if your technique and timing is good, you'll drop anyone, especially if they are charging. this technique is very useful in fighting situations because it's quick, efficient, and devastating. also, a well placed back kick will make size and strength differences meaningless, the bigger they are, the more your strike will hurt them as they charge into it. but remember, back kick is a defensive technique!

The easiest way to deal with it for me would be to feint high and tackle. Then I could either put him in a lock or attack a soft spot/vital point. The initial impact of his head with the ground is a good stunner, anyway.

The best way to improve your reaction ability and timing is to spar. This is the closest to a real-life situation you can get, so it's a good idea to make the most of it. Wear armour so you can spar with less rules and therefore make it more like a real fight. Choose opponents who are superior fighters so as to learn more from the experience.

The rest is just practice and determination.

I'm not sure what you mean by "real life" but I've experienced couple of fights off the ring before I've started martial arts. My opinion is that street fighting against an amateur is much more easier and less stressful compared to fighting in tournaments. I think that if you experience not just sparring but fighting in the tournaments, it would be good enough for average street fights. If someone charges at you, circle around and dodge them or think of a way to counter them depending on how they charge at you(punch, knee, elbow, kick, throw, etc.). It's a street fight and not a tournament. If the guy charges at you while lowering their head, just drop and elbow as hard as you can on the back of their head. Now for someone who has skills and experience, dropping the "entire weight" on the back of the "neck" would be lethal since it would damage the spinal, but back of the head would most likely just give them a lot of pain.

The only thing I'm sure about complete amateurs is that they can't take any hits so all I'll think about is landing an easy shot like a jab to the eye, nose, or mouth or a strike to the body while trying not to hit the rib cage. If you're not skilled enough to fight and defend yourself while not hurting your opponent then just think about hurting the opponent or else you'll just end up getting hurt. There's no need to be nice towards someone that bring you an unwanted fight to you anyways.

The longer you train, the more ingrained the techniques become. I was surprised at my ability to snap into the proper defensive position in an emergency. You should have seen the other guy's eyes pop.

Give him a high crouch and flatten him

you just sprawl and make him eat concrete what's so complicated...

Someone did charge at me once. He ran at me with the intention tackling or slamming his body into me. I stepped off the line at the last second, grabbed the back of his neck and the belt of his pants and pushed him past me and almost sent him into a wall.

Can't think of any other way to change my reaction to a scenario other than practicing with repetition.

for starters always try to avoid confrontation if you don't want to end up in a fight, don't mess with people they won't mess with you. now to answer your question depending on your confidence to the situation if someone is charging at you keep your composer and do your best to dodge the attack then apply your training and subdue your opponent, that's how I would react. never freak out or you might get clobbered.

I would keep my cool, and use technique. I would use my strengths against him. I would use the moves that I use best in sparring, and make him react to me. For example im a very good groundfighter so I would fight on the ground were im most comfortable.

I would drill self defense situations and let my sparring partners use 100% intesity. You got to work on your composer.