|Music is more than simply playing the rhythms and the notes that we read or are taught. Music has emotion, too. Expressing and using that emotion is absolutely essential in a great performance, but it can also be a valuable tool in practicing.
When you practice a piece, play it the way you think the composer heard it in his head. Is the song happy or sad? Maybe it is scary or excited. Express the emotion in your playing. Getting those emotions across to your listener is part of the fun of playing music.
Next, try playing it using other emotions or feelings. How do you think you can you make Twinkle Twinkle Little Star sound happy or sad? Play it that way! Play like the music is angry, or like it is sneaking around. What happens if you start loud and get soft, or the other way around? What about starting slowly and getting faster? Or s-l-o-w-i-n-g d-o-w-n? If you have learned vibrato, use it. If you always use vibrato, take it away. Try using different bowing techniques so you can change the way a song sounds.
Approaching music from a variety of perspectives helps you to see things in the music that you never, ever imagined. And putting some fun and variety into practice can really help your attitude. Just don't forget to practice some of what your teacher wants, too!