How can I teach my children to be happy in a world which seems to contain such unbelievable heartache?

With events like tsunamis, nuclear disasters, tornadoes, fiscal ruin, etc., I am not even sure myself where to find happiness and meaning. I believe in God, and want to believe that He cares about us, but I find every pursuit I choose to be vain, self-serving, or hollow, and God does not seem to answer, when I ask Him for guidance. It just seems like everything has no meaning or purpose, except what I choose to derive from it.