It seems to be inevitable...
I start the first 4 or 5 holes off real well, usually no more than 2 over. Then, around the 6th hole on the front, I fall apart for some reason. Same thing happens on the back nine.
This happened to me yesterday. I started off even after the first four holes, then fell apart around the 6th hole and ended up with a 44 on the front. Then, on the back, I started off 1 over after 4 holes, then fell apart. I landed on the green on a 170 yard par 3, then proceeded to four putt.

After the four putt, it was down hill. I seem to lose my mental edge and my game goes to ****.
This seems to happen to me nearly every round. I shoot in the high 80s quite often, but I know I'm good enough (physically) to shoot mid to low 80s, if I could just keep my head in the game. I generally try to look ahead to the next shot, but after a 4 putt, it's tough.
It's almost like somewhere in the back of my head, I'm afraid to let myself shoot a good round.
How do you guys cope with this insane game and your blatant mental lapses?
