Click on the link above, it brings together multiple aspects of visualization and its use with athletes.
Like athletes, actors have to deal with the desire to:
do more creative, detailed work,
do more competitive work (in order to book jobs),
the desire to unleash our creativity,
the need to address fear and anxiety,
the pressure placed upon us and upon our performance-in auditions and on set/ stage.
Research the technique of visualization as it is used by athletes (and many others), and you will find that the effectiveness stems from taking the time, creating with detail, having a goal--and your belief!
If you choose to use visualization, you will find that you can create a way of working that feels right for you, your instrument and whatever you are working on. Visualization involves breathing, the imagination, and letting go of the pressure placed on you (by agent/manager/ parent/ spouse) long enough to bring your creativity and joy to the forefront of your work--allowing you to come that much closer to your potential.