While seated comfortably or lying down, picture one of your best bowling performances. Recall the center where you were bowling, the ball(s) you threw, and the people on the pair. Picture your perfect execution for a strike, including the ball motion from the laydown through the pins. Most importantly, remember the feelings of confidence, control, and freedom of your best performances.
Repeat this process several times per week leading up to an important competition to help build confidence and reinforce your peak performance mindset.