"Purpose Tremor"

 

Attempting to pour a liquid into the mouth of a very small-necked bottle often results in the same kind of behavior. You can hold your hand perfectly steady, until you try to accomplish your purpose, then for some strange reason you quiver and shake.
 In medical circles, we call this "purpose tremor".
 It occurs, as above, in normal people when they try too hard, or are "too careful" not to make an error in accomplishing some purpose.
...Excessive carefulness, or being too anxious not to make an error is a form of excessive negative feedback. As in the case of the stutterer, who attempts to anticipate possible errors and be overly-careful not to make them - the result is inhibition and deterioration of performance. 

From Psycho-Cybernetics by Maxwell Maltz (pp. 173-174)

From time to time you see an athlete who is holding on so tight to their goals that it is counter-productive to generating the kind of performance needed to achieve them. In the immortal words of .38 Special, you need to "Hold on loosely, but don't let go. If you cling too tightly, you're gonna lose control."

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