Being optimistic and being happy are totally different things.
I'd say someone feels optimistic when he only looks at the positive side of a situation, while happiness is a state of emotion. I'm mostly optimistic that tomorrow will be great, but it doesn't mean I'm happy unless someone promised me a nice package (lol, I was actually hoping my dad would return home with a package for me tomorrow).
Well, I wish you all the success in the world with the happiness that that package can bring you tomorrow. Always with optimism ahead.