You just walked off the course after shooting 10 strokes above your index. You struggled to find the fairway and your approaches often missed by several yards. Worse yet, you tried everything to get back on track but nothing worked.
High-tail it to the practice area, tee up five balls as shown, and without allowing a single swing thought or mechanical idea to creep into your head, take a few quick practice swings and then start blasting away. Hold your finish briefly, then step to the next ball and start your swing without hesitating or stalling. Don't worry about where the ball goes, and don't make any adjustments from one ball to the next. The only thing you should focus on is ending each swing in balance. This drill instills the feeling of a free-flowing motion, something that can and will come and go over the course of a season. Repeat this drill a few times. By the tenth ball or so, you'll recognize the old feel of your good swing.