Your question presupposes that there is a plan for the universe and you are searching to find your part in delivering it.  This is the foundation of many belief systems and the basis of abuse by some spiritual leaders in imposing their own agendas in the guise of their chosen deity's. By asking a loaded question like this you remove the freedom to explore what your existence really means to you.

If the universe is, as many believe, governed purely by physical laws and cause and effect, then it is entirely up to you what meaning you give to your existence.  Just make it count.

My mother once challenged me to explain, if I was so clever, why we were here.  I pointed out that in my particular case she was better informed than me.