Young athletes should practice with intention and complete focus. Focused practice should mimic the level of focus that is required in competition. Your kids should mimic what happens in competition with the same level of focus. This requires a baseball player to use the same intensity and focus in the batting cage as they do in a game.
Teach your athletes to have a good mental game in practice so they can transfer practice to competition. Ask your athletes to use their full at-bat or preshot routine with 50% of the time. But a pre-shot routine should feel natural to perform. Help your athletes perform in practice how they perform in competition.
Check out The Focused Athlete program for more strategies to focus your best in competition.