Sometimes it's not so much about what we celebrate than that we celebrate. We make up reasons to celebrate to lift ourselves out of the rut, day-to-day life, the ordinary. Think yin and yang. Whether it's a birthday, a milestone, or a national holiday - they are all great reasons to celebrate.
We thrive on being with people, sharing food with people, talking with people, doing things with people. And that's what celebrations are about. Getting out of the office, out of bed, out of everyday life and making an effort. Of course it's more of an effort if the celebration is at your own house than if you are just visiting somewhere. But we all take turns between being invited and being hosts. And why not look at party prep time as playtime, using the reason for the celebration as a theme for food and decorations and even games. I know people who knock themselves out with party themes so it all matches, food included. That can be a lot of fun.