No one on the planet cares as much about your work as you do. No one. I like to say that I do, but that is not realistic. You care about your own work, success, and accomplishments more than anyone else possibly could. Think about it.
Believe it or not, it is not within teachers' job descriptions to write college recommendation letters! So, once your teacher has agreed to write a letter on your behalf, take the time to thank him or her for agreeing to write the recommendation.