Guess what it is? I'm glad and happy... it's an achievement of satisfaction! You can't measure it with any material stuff including money!
It's SEEING YOUR STUDENTS IMPROVE in their learning everyday!
I just found out I connected well with those music students whom I nearly gave up on them! They were not bright student and they didn't pay much attention during the lesson or never practise the piano even I persuaded and buy them sweets to encourage them moving on. I didn't like when it's their lesson slot (yes, I got to be frank to you all that teacher do have preferred students, OK?) and hope the time passed faster. LOL! I was a terrible teacher.
But lately seeing that they really pour hard work and effort at last makes me feel joyful. Be it for the concert or the coming exam... I know they are serious this time as I can see they are improving. My students are like my children, no matter how bad they are, as long as I don't give up on them... they are the hope of the future.
Moral of the story: It's tough to become an educator. Same goes to parenting too!