It really depends on who you are! As a Christian, I feel as though it is to make the world a better place when I leave, and to follow God, His word, and His teachings.
But maybe you are not Christian, and that's okay. Maybe for you, it could be to make those around you happier. Also figuring out or choosing a purpose for your life will make it worth while.
Like other people have said, maybe to be loved or love. Even pizza! ;)
I can't decide for you what the meaning of life is. You have to make that choice. Just remember, life is what YOU make it! Keep your head high, Jessie! Good luck!