What does conditioning have to do with taking punches?

This for sure, having a solid neck helps with punch resistance but when you're tired you lose that. There's also the fact that great conditioning helps you get back up, like someone else mentioned with Calzaghe.

 

you felt anxiety? you have a vagina, dont u?

 

I dont know the correct answer to this, but the first thing that comes to mind is that if a boxer is in good shape he is mentally stronger too, very simple! And ofcourse, a stronger neck does make wonders

 

Just to add to this slightly the Neck musle theory is mainly based off of Holyfield but it is true . Hooks usually cause the most knockout's but it's due to rapid snapping of the head which causes the brain to to go out of it it's protective layer of liquid and hit against the skull thus causing bruising of the brain with results in knockdowns and KO's. In short building up neck muscles will make your head snap less and like i said the advantage of being in great condition you will recover quickly ...as far as taking a punch that's beyond science it's impossible to build muscle on your chin and balls only 2 places not joking why some fighters can take murderous hell like Lamotta and other fighters like lets say the KO king Randall Bailey get's knocked down by feather-fisters is a mystery of sorts It's speculated it has to do with heart or maybe a refusual to yield mentality but there's no definitive answer.

 

Think of it this way. Boxing is an organized, controlled, "Flight or Fight" response where you've basically chose to fight.
When you're put in a tense situation, your heart rate goes up and your first reaction is to take yourself out of the dangerous situation. When your adrenaline clears, you're possibly going to feel out of breath, light headed, things like that. Same reason you need to be conditioned to fight in the military and things like that, your body needs to be capable of removing itself from a dangerous situation and conditioning is the key to that.