What is being a teacher all about?

The first thing that comes to my mind about why teachers are so important, is that we impact the future people of our world.  The last few weeks I have felt very disconnected and overwhelmed with my job.  I feel as though I am not impacting the kids and it is hard to think about that.  So many of them come in excited about what we might learn and I have been a disappointment as of late.  I just cannot do it all and for some reason, someone thought I could.  Even I did for a little while, but as a new teacher, how much did I really know about what it entails to be a teacher?  No much.  I think I'm learning that there is fine line between the feeling of letting the kids down and the feeling of letting yourself down and that is the biggest struggle for me.  I wish so bad I had that moment this week or even the last few weeks of knowing I'm making a difference as a teacher to these students, but I haven't.  How do I get motivated again?