And you'll be enthusiastic! The key to teaching, for me at least, has been to promote an air of excitement in the classroom. I aim to make my classroom culture one of discovery and wonder; I want my kids to see the connections that mathematics has with their lives.
The first step to doing this in a classroom is to be the most excited person in the room. If you bring the energy and the smile, students will follow.
The second, and essential step, is showing kids how mathematics is worthwhile. To do this, you have to give them real world uses for math. The higher the math, the more difficult this is to do.
A website I have been exploring to do this is http://www.mathalicious.com/. It is a site that supports common core math lessons with real world circumstances. It is easily searchable by grade level an topic. For instance, I am currently working with probability with my high school students. I found three lessons that connect probability calculations with lessons that connect to sports.
The site provides the standards, prerequisite knowledge, student handouts, and a lesson guide. While all of these are extremely useful (especially for a person with no sports knowledge!), it is still important for the teacher to work through the materials first before incorporating these tools into a class lesson.
