Competition in sport is healthy and natural, and sport psychology is the discipline best suited to optimize performance. Any psychology must place the welfare of the individual first, and carefully preserve intrinsic motivation. Performance can always improve, but the best sport psychology advice for parents is often to just take it easy. A young performer who has truly discovered their sport will be internally motivated, excited, and pursuing improvement. However, this attitude isn't created out of thin air.
Individuals discover their sports and mature at varying rates, and in different ways.
Although you've always preached the value of success to your kids, the state championship might not be tops on the agenda for an adolescent struggling with academics and social development. Motivation is complex, comes from deep within, and cannot simply be attached to a person like a motor bolted onto a speed boat. If it were that simple, psychologists might lose their shirts to motivational speakers, or even employees at the psychic friends network. Praise sport and demonstrate the joy of competition and improvement, but realize that external demands or pressure on a child ruins their fun and sabotages your purpose. Let your child discover sport without providing the benefits of negativity, pressure, expectation, or punishment.