You can’t make your preteen love middle school, but you can motivate him to do well there. First, though, you need to figure out what doing well means. If your idea of a job well done involves nothing less than straight A’s you should rethink some things. It’s unwise—and unreasonable--to demand perfection from your preteen, especially during the middle-school years.
This doesn’t mean you shouldn’t expect him to do well. It just means that you need to be reasonable. If you’re not sure what “reasonable” looks like, talk to his teachers or guidance counselor. They may be able to offer some insight about his abilities.
Beyond that, help your middle schooler stay motivated by modeling motivation yourself. Show him what a motivated person looks like. Talk to him about your own struggles. Let him see you work toward your goals—even if you stumble along the way. “This sales report kept me up for a few nights, but I finally finished it!” Let him share your successes and your failures. To motivate your middle schooler even more:
  • Encourage him. Middle schoolers need love and support from their parents (no matter what they may say). Sometimes, putting your arm around you middle schooler’s shoulder may be all it takes to get him through a rough patch.
  • Use realistic praise. Don’t call you preteen a “genius” just because she did so-so on a test. He’ll see right through it. Instead, use more down-to-earth words like “creative” or “hard-working.” Show your preteen that you notice theses real qualities in him.
  • Let him make his own choices. Whenever possible, have your preteen make decisions. By giving him the freedom to make his own choices—even if it’s about something as simple as what color shoes to buy—he’ll realize that his input is important. And feeling important is a great motivator.

http://www.mohonasen.org/03parents/MSParent/slacker2scholar.htm Source: "From slacker to scholar: Helping to motivate your middle schooler," Mohonasen Central School District