I celebrate myself, And what I assume you shall assume, For every atom belonging to me as good belongs to you.
In 1891, though, Whitman revised Leaves of Grass and added three words that I think drastically change the opening of "Song of Myself."
I celebrate myself, and sing myself
It is important to celebrate yourself, for you are special and unique. However, if you do not share that with the rest of us, then we are all the poorer for it. Allow others to see who you really are and what you have to offer.
To do that you must first find out who you are, who you want to be; your dreams, hopes, beliefs. Then live life as fully as you can, as only you can.
Then celebrate who you are and sing who you are.