I want to quit again!

I started giving tuition a week after the NCS contract ended.
I'm actually not qualified to teach.
I make a lot of mistakes and not good in explaining.
However, it is impossible for me to quit now.
I have to complete the whole year and now we are in January only.
I still have 11 months to go.

I wonder why I can't stick to a job. =(
Every time I face problem, I just want to quit, quit, quit...
That is my bad habit.
Yes, I am selfish.