High school French teacher checking in....as far as making a difference, I think at the high school level you may never know if you made a difference or not. I say that because some students are just motivated regardless of what I do, and to others a smile on a bad day may make a difference.
I fell into teaching when I went back for my MA after a semester off and working in the computer industry. I was a TA at the university and had a good time teaching there. One of my MA colleagues had an opening at his school for a French and German teacher - I interviewed and got the job. I'm now at a different school and only teaching French (my passion). Some people say that anyone can be a teacher, but I really don't think that is true. If anyone could do it, more people would stay.

Had I listened to my grandma when I was 15, I would have been a teacher from the start- she knew I had it in me.
Best wishes to all GC teachers and student teachers for a successful academic year. Keep up with the professional development!