"Have you ever built a snowman?" After all, snowmen are ephemeral objects, soon to be melted in the sun. A snowman has no ultimate purpose or goal, and in a few weeks there will be no trace of it's ever existing. We build snowmen because all of us, theists and atheists, live here and now. In the context of our own brief mortal lives, we are able to enjoy this life and gain pleasure from ultimately pointless acts. It is fun to build a snowman, or climb a mountain, or watch the sunset, or go for a long cycle ride in the countryside. The purpose of these things is not "out there" somewhere, waiting to be achieved - the meaning is in what it means to ourselves. I am not overly concerned about some future fifty billion years from now, but I am concerned about the future of humanity here, now and for the generations that follow. That is the context of a mortal life, and that is why I "bother" to live and damn well have fun while I'm doing it.
There is no meaning to life itself. There is no purpose to the universe. You can, however, give life meaning through your actions. Make the world a better place for yourself, your contemporaries and your descendents.