Why should we celebrate birthdays?

It remains 7 months for my birthday and I wonder why celebrate? I'm not interested in celebrating my birthday anymore, "All behavior is learned" I've never learned to celebrate it, I rather the idea of celebrating every day of my live, how? ... doing what I like: reading, writing, listening to RAP and enjoying my solitude.

Celebrate everytime of your life

 And you,... how do you celebrate your existence?