How do I deal with a co-worker that gripes non-stop? I've tried everything I can think of.?

We work in a restaurant, and every morning she starts griping about what "the lazy people" didn't do the night before, and shes tired of having to do it, and on, and on, and on, I tell her let it go, it's not worth it to get yourself in a bad mood. Just do the work, and get on with the day, she drives me insane, but I try not to let it get to me. I don't like nag nag nag. But, this gets tiresome to have to tell her she does a good job,she's a good worker, I appreciate what you do & all that jazz! HELP!!!