As coach it is your responsibility to keep your athletes from being bored during practice. When your players are bored with practice they lack concentration and focus. Make practice goal-oriented by establishing a goal for each specific task you are going to work on in practice. Goal-oriented practice help athletes focus by giving them a task with a specific goal to accomplish.
A good time to establish goals for any practice is after a game or competition. Meet with your assistant coaches and go over the things that the team or individual needs to improve especially while they are still fresh in your mind. Write down your objectives for the next week. Use a challenge for the players at the next practice that will help them improve.
Check out the Mental Game Coaching Professional course for more information on coaching the mental game.