Decision of Happiness

When does a decision becomes right? Is it when you create happiness for others or is it when you create happiness for yourself? A decision where one has to sacrifice his own happiness for the sake of another, isn't that the right way to think? I've been pondering over this for quite sometime now. I guess you must follow whatever it is that makes you happy for in the end a decision which lacks the necessary ingredients will consume you whole. The right decision is when you create happiness not only for yourself but for that person as well. You have to reanalyze whether that person's happiness will mark your own happiness...