I have to go to School still
You'll have to go at university after school, so enjoy your time now while you can
It will be a lot harder in a future
Of course, new friends, new experience - life is great.
So, I wish you many many birthdays after this one.
PS. As I had the flue, my birthday party wiil be tomorrow, and I'm very happy all my friends will be with me. So have a great party too, as 19 is only once in your life.