First and fore-most, you must have confidence. Your second mental problem is concentration. Think the shot through in advance before you address the ball. Draw a mental image of where you want it to go and then eliminate everything else from your mind, except how you are going to get the ball into that preferred spot.
Sam SneadTo be consistently effective, you must put a certain distance between yourself and what happens to you on the golf course. This is not indifference, it's detachment.
Sam Snead