Continuing with Marianne Williamson's poem about our Deepest Fear..
Later in the poem she states
"And as we let our own light shine, we unconsciously give other people permission to do the same. As we're liberated from our own fear, our presence automatically liberates others."
From a Buddhist perspective, we do these practices not solely for ourselves, but for the sake of all beings (who we interact with). These lines help to explain how our practice and us changing helps to change the world (or my tiny part of it). How I become a candle that lights the candle in the person next to me.
If it feels too self-centered to celebrate your worth, do it for your children, family, friends. By shining your light, they will know that it is ok FOR THEM to do so as well.