The worst thing you can do is to force yourself to do something that you don't really want to do, or act like you are into something when you aren't really all there. Just go with the flow and let yourself feel whatever it is you feel. Be genuine today. And if that means being in a grumpy mood or wanting to be alone all day long, then so be it. The people who support you when you're cheerful and outgoing will support you when you're sullen and quiet.