As a beginner, golfers are more occupied with fundamentals and swing mechanics than they are with making mental mistakes. As a golfer gradually becomes better and better, mental mistakes are more likely to have a negative effect on scores than the aforementioned. In fact, it has been said that golf is 90% mental and 10% physical. A mental mistake can be made at any time during a golf round. Recognizing and having the ability to avoid them in the future is a characteristic of all better players and one more key to having a consistent and reliable golf game. Below is a list of some common mistakes and steps you can take to avoid or minimize them.
Expecting Too Much from Yourself:
One of the most common and biggest mistakes that a golfer makes is putting a lot of pressure on himself by expecting too much. Have you ever shot that once in a lifetime score and felt that you should be able to shoot that kind of score all the time? Trying to chase a once in a lifetime score promotes self-created pressure, which one needs to eliminate if he wants to become a better golfer. Expectation demands that we should play in a certain way, and if we don’t, it leads us to frustration and self-doubt. Having too high expectations of yourself is one of the biggest causes of a loss of self-confidence and not playing to your potential.
Instead: After a once in a lifetime score don’t keep score for the next round or two. Focus on your pre-shot routine and play only one shot at a time; this will help you focus on your process and when the process is right, the outcome will automatically be good.
Focusing on What You Don’t Want to Happen: Mental blocks and challenges arise when you focus on what you don’t want to happen instead of what you do want to happen. When you focus on what you don’t want, that is usually what you get. For example, when you focus on not hitting the ball into the water, then what would be the first thing that your mind visualizes. The first picture that would come in your mind would be the water and most likely that is where you ball is going to end up.
Instead: The golf swing is executed with the subconscious mind and it does not understand negative. That is why when you think “I don’t want to hit the ball in the water”, your subconscious will immediately thinks about hitting the ball in to the water. Forget about the water and visualize yourself playing to your target.
Taking a Negative Emotion from One Bad Shot to the Next Shot: Most golfers of lesser ability make the mistake of taking their negative emotion from one bad shot to the next shot. Everyone plays a bad shot; even better players and professionals. Verbalizing and thinking about a bad shot imprints the subconscious with thinking that a bad shot is acceptable. Thus, a similar situation on a future shot is likely to result in another bad shot.
Instead: As hard as it may be to do, forget about your bad shots. Think to yourself, “What is my goal for the next shot?” and focus on that. When you make a good shot, do not think of the ways it could have been better. Accept it and visualize what it felt and looked like. That is what you want your subconscious to remember.
Playing a Shot When You are Not Ready: Sometimes golfers feel they have to hurry up with their shot because people are watching them. Other times they take their shot even though they knew something wasn’t right. What ever the reason, taking a shot when not ready is likely to lead to a bad shot.
Instead: Whenever you feel that you are not mentally prepared or ready to play a shot, back-off and start all over again. You will stand a much better chance of making a good shot if you are mentally ready.
Going Against Your Own Gut-instinct: Although the subconscious mind is going to make the best shot given the circumstances, it is the conscious mind that makes the decision of what club to use, wind conditions, yardage, etc. The idea is to match your conscious decision with what your subconscious knows. Your subconscious mind knows everything about your abilities and your game, and it also knows the shot you should choose to hit. When something does not feel right it is because you have not matched your conscious decision with your subconscious ability.
Instead: Know your abilities and learn to listen and trust your gut-instincts as most of time it is going to be right.
One of the differences between a mediocre player and a better player is a follows: A mediocre player has a couple bad holes and thinks that their round is not going to be a good one. A better player has a couple bad holes and knows that they can still make some pars and possibly birdies to make up for the bad ones, resulting in an acceptable score.
Ron Celano's Blog 
Great post Ron.
Really enjoying the series and shared it! Niuce work!