I can't do this and I've been playing for 13 years. I hate it.....never been able to do it. I can't even talk while I play haha. I'm always concentrating on what I'm playing and if I try to think of words that I'm supposed to say/think, everything just falls apart.

It comes easier to some for no reason really. Take a look at people like Alexi Laiho from Children of Bodom. Lead guitarist that SHREDS and also the lead singer of the band. Impossible for some.