blunders,and how to avoid them?

Blunders, and how to avoid them?

First of all, I'm not a chess-master or a high-ranked player. I play for fun, mostly good strong game until a blunder comes. It's not that I don't follow the game, it's as if I get blindfold on my mind and then make the move. "Submit", oooh no, not again. There goes a pawn, or a Bishop or a Knight and then the game might as well be over just then. I really get frustrated on my self. Never the less I always play the game to the end just to see how the opponent is going to use my blunder to win the game. Most of them did just that, but some didn't, while some made even worse blunders them selves and lost while leading the game. I played some nice games during these few months online and I still win more than I loose, but I made some horrible mistakes that I can't forget. And I know that I have more of them to come. 

So tell me, why do we do it? And, do we learn from our mistakes?

Please comment.. Good luck to you all.

May you blunder less...