Your game has completely fallen to pieces in the middle of your round -- each shot seems worse than before, and you're ready to walk off the course.
You may be hitting some bad shots, but the main reason that the wheels have started to fall off is that your mind has begun to play tricks on you. You look back at the series of bad shots you've hit, and you then project into the future that the bad shots are going to continue. And they do -- because it's a selffulfilling prophecy. Here's how to break this destructive cycle:
Lose your aggressiveness
When things are going bad, you naturally get aggressive. Unfortunately, this approach is guaranteed to make things worse. Go the opposite way play every shot as safely as you can. Don't go at the flag play to the front of the green (not even the fat part, just the front) and rely on your short game.
Use the five-second rule
After every shot, you get only five seconds to make a quick evaluation of what you did right and what you did wrong. That's it. After the five seconds is up, the shot is in the past you can't go there anymore.