I want to get better.
I am getting stronger.
The song became popular.
She turned red.
He grew old.
When we speak about a state which changed, we often use get, become, fall, turn or grow and some adjective.
The words which you need to know for Level 2 are
get better, get married, get, stronger, get tired, get used to, get worse, become popular, fall asleep, fall in love, turn red, grow old.
You can see more examples in the book The Little Prince.