A bird does not sing because it has an answer. It sings because it has a song. Chinese Proverb
Technically, birds sing for lots of different reasons like attracting mates and claiming their territory. But lets not ruin a beautiful and inspirational quote with science and logic.
You are a unique person. No one on earth before or after you will be just like you. No one has the same fingerprints, the same DNA, or the same shaped heart. No one has the same experiences, the same combination of strengths and weaknesses, or the same understanding of the world.
You are unique. You have contributions only you can make, problems only you can solve, and wishes only you can fulfill.
Give, because you have a unique song to sing, and I want to hear your music.