It's the biggest problem a motorcyclist faces when trying to improve his/her riding.
Fear is fueled by the belief that: "I can't do it".
If you are afraid of taking a turn 10 miles faster than you usually do, your survival mechanisms will make you incapable of going through the barrier and improve your riding.
This is a frustrating situation.
Obviously fear is a good thing, necessary for survival, so we must learn to work with it rather than be possessed by it. Fear can be your worst enemy if you do not know how to control it.
Every person has what can be called: fear threshold, that's the point at which fear takes over and the rider can't operate properly anymore. Usually right before crashing the rider will think: "Oh!....I am going to crash" and that's exactly what happens.
Remember: If you think you will or you think you won't, you are right!
It is your belief of the outcome that makes it real. Confidence is a state of mind based in your knowledge. Confidence is the force of imagination, your mind's ability to imagine the possible is the real creative force.
If taking a turn you start to slide...
What is your reaction?
You will probably get scared, then you get very tense and your mind stops thinking properly (fear is taking over) and your possibilities of crashing have been increased significantly.
Learning to stay cool and keep calm requires practice, LOTS OF PRACTICE.
Only by practicing "sliding" will you become comfortable enough with it that you will no be blocked by fear when it happens. As you experiment with sliding you will learn that's nothing that you can do and you will let it happen without fighting it. Then when it happens on the road, you will be able to deal with it without "over-reacting" with fear....locking the tires and going straight off the shoulder.