It may feel like Christmas break or the end of the school year will never come. You may have a class that misbehaves so much that that you go home and cry every day after school. These things happen.
The only way to handle these difficult situations is try to not think about too much at once. Having to deal with that wild class for 175 more days may be more than you want to deal with. But one more day is manageable.
If you are having a tough year, try not to think about the challenge of having to last for the entire school year. Just get yourself ready for tomorrow.