The shooting process entails both technical and mental elements. The technical elements include having a correct stable stance, break point and muzzle hold points that allow the shooter to have a smooth controlled swing that develops the correct muzzle/target relationship at the break point.
The mental elements to controlling ones nerves during competition, can be achieved in part by having a pre-shot routine that get the body and mind in sync while shutting out the rest of the world.
Physical fitness training increases stamina, core stability, and upper body strength. Yoga is a good overall fitness activity.
Visualization involves mentally going through every step of the shooting process, seeing the clay target break into a starburst of small pieces, and smelling the gunpowder.