Purpose of Living.

For a long time, I've been wondering..
What are we, humans, living on Earth for when we will all die eventually?
I'm not a Christian, so I don't quite believe that God has placed a purpose in our lives.
I don't believe that there is actually Heaven where you go and spent your afterlife.
I mean.. What if you actually die and find that there is no Heaven?
I don't get the purpose of living, and I'm tired of living(Somehow).
Being a kid who wants to grow up, being a student who studies all day long, being a adult who works to struggle with life or marriage, being a oldwoman who is there waiting for life to end.
It all leads to death in the end, so why do we have to struggle so hard to live on?

I think this big question mark will be in my head for a long period of time eh.
For now, I think that, I just have to live, to search for my purpose of living, to do my best, to be remembered by others, to not let those people who care, worry.

Gosh, I sound so emo! -o-
No, I won't go and cut myself up or end my life, stupid! HAHAHA
I just don't get what's living for, seriously.