The problem with practice is that is can seem like work. When it does, it’s not very productive. They call it “playing” an instrument for a reason.
There is a fine balance between play and work when you’ve got your instrument in your hands. Practice as work involves systematic, goal-oriented activity. Practice as play involves “noodling around,” having fun making noise. Both of these types of practice are productive in their own way. When you take practice seriously, adhering to a plan, you strengthen your technique. But when you explore the instrument freely, you learn the language of music in a very natural way. I believe the best students do not need to be told how often to practice, because they pick up their instruments out of compulsion. The challenge in teaching a natural learner is to keep them on the curriculum.
When a student lacks motivation to practice, the challenge is to help them find a connection with their instrument. Graded repertoire, method books, and technical exercises are only helpful when a student already feels excited about working on them and improving their skill. First, they must develop a love for the instrument.
In some cases, a student already possesses motivation. You can identify them by how much they learn outside of what you assign. I sometimes have guitar students who independently learn songs via online tablature sites like Songsterr, or browse YouTube for instructional videos. They are a rare treat, and also not as likely to stick around because they are more capable than others of learning on their own. To retain them, challenge them. Most other students, however, begin not only as novices in the art of performing, but as people who might not have yet felt a passion for playing.
Four of the five tips in the TakeLessons article, “Use the word ‘play’,” “Be creative,” “Create a pleasant environment,” and “There’s no room for criticism,” are helpful for the parent in allowing a student’s passion to bloom. But the fifth, “Find the right teacher,” puts the onus on the instructor to be the right teacher. As an instructor, I not only hold myself responsible for teaching how to perform, but also for inspiring the student to spend time with their instrument, whatever they do with that time.