In this world, no one is irreplaceable. 

If you missed your chance, someone else will take it. If you don't turn up for an audition, the show goes on.  If you don't perform well at work, your boss can always hire another. If you break up, you'll find the right "next" one. Really, the world moves on with or without you. Yet, at the same time, no one can be replaced. There is only one you, and no one is exactly the way you are. Coco Chanel says, "If you want to be irreplaceable, you got to be different." True. But I think, 

"If you want to be irreplaceable, just be yourself!" 

Even when we are replaceable, be irreplaceable.

Be what you are meant to be, especially to the ones you love.