Read what Flechas said, I think he has the right idea.
Meanwhile, if you are getting bored and tired of it already, your students will pick up on that. I've seen more than one instructor take advantage of students just to build time, cancel on a whim to do something 'better', and then take advantage again when they didn't have another option at the time (read: right now). Don't be one of those instructors, you were there once. I'd wager that you have had an instructor do that to you. Remember that and don't be "that guy". Sure it gets old teaching steep turns and slow flight, but that is what you are being paid to do. When you are flight instructing (and doing your best at it) you are gaining valuable experience, as you are the one making the decisions. You will realize this someday when you go to training at your first flying job that revolves around getting people/things from point A to point B.
I'll stop now, I don't want to "preach". Hang in there, keep a good attitude, and do your students right. Not too many people want to be an educator for the rest of their life, and that is fine. At the rate you're going you will be able to move on quickly. Just make sure when it comes time to leave you aren't feeling guilty about how you have treated others (who are looking up to you) along the way.