The best way to motivate yourself is to just think about your future; Think of how far you want to go, your chosen university, the great time you'll have there, the new opportunities, new people, new societies! It's just a year for your entire life. I know it may be hard, but you'll really regret it later on if you don't put the effort in.
If you go on through this, you'll make yourself proud (and trust me, nothing is as exhilarating as academic success!)
Everything you do now, will return to you in the future. Don't let any bully or other idiot take it away from you!