Nothing

A person can disappear from this world.  I saw a dead baby deer on the highway, and her mama and litter mates will know she's gone.  They will mourn her in their way.  Someone told me I must choose joy, and keep choosing joy every day.  What is joy?  What is happiness?  I was born without these things.  I was born missing several essential pieces, truth be known.  Choose joy?  I'm alone in the world.  Totally. Completely.  I don't know "choose" or "joy."  I know how to behave.  I know how to be invisible, but I don't know how to not be invisible.