The Four Mental Steps
1. Feedback / Response
After you have hit the golf ball, LEARN from that experience. All of your successes and failures are LEARNING opportunities if you use the right feedback. Make a mental note of what you did RIGHT and store it away for the future. Not what you could have done better (not criticism!) and tell yourself to make the necessary adjustments in the future.
Whenever you react negatively to a situation, tell yourself to relax and become more OBJECTIVE so you can learn to use your feedback. As you walk to your next shot, relax. Enjoy your surroundings and your companions. Have fun and be happy that you can enjoy such a fine game.
As you approach your ball, accept any and all challenges. Focus and prepare for your next shot. Also, make sure your intensity level is appropriate for the task at hand. If you are overly excited, or too relaxed, you will be out of your optimal intensity range and your performance will suffer.
Being prepared is one of the keys to success. Practice and develop your mechanical skills to match your performance expectations. Learn to master your emotions. Practice POSITIVE self-talk.
4. Instinctive Execution
Once you step up to the ball and are set, just go for it! If you find yourself thinking too much at the point of execution, go back to steps two and three. Then go for it and see what happens at step one. Have fun and enjoy the PROCESS. Don't worry about the results.
Start using the four-step routine by teeing off the first hole of an imaginary round of golf. You are relaxed and prepared to play up to your expectations or within your limitations. Hit the ball mentally and see the result. Now, you are ready to step up to your first tee shot.
P.S.: A major difference in the golf scores of pro's versus those of high handicappers is not only the swing, but also the way they think and how they approach situations. Here is a book that explains how the pros think and why you should start thinking that way too!