That’s an easy one, because you don’t have to do anything!
Unlike most of the other holidays, the requirements to celebrate chanukah are something everyone can do, be joyous, light the menorah say some blessings and eat oily foods, easy stuff – especially if you don’t keep much of anything else. Add to that, the fact that even the most secular Jews feel a little bit out of place when it comes to celebrating Christmas so you have this sort of Chanukah resurgence to make these secular folks feel like they have a holiday too.
What’s not to love about Chanukah, the davening isn’t that much longer, there are no yuntiff requirements (I’m sure someone will give me a thesis in the comments about all the things you aren’t supposed to do on chanukah, like celebrate our new age Hellinism by watching TV while the menorah is lit) you don’t have to dress up, you don’t have to go anywhere special, save for some lame chanukah parties that were billed as really cool.
If you think about it, it is a bit weird that the one holiday in which all assimilated, intermarried and non-observant Jews come out in full force to celebrate is the holiday that was caused by our own assimilation. Or is it not possible for them to be modern day hellinists when they are in fact celebrating a Jewish holiday which is publicly declaring us Jews, nothing says Jewish more than Chanukah – even though most people keep it as the superficial electric menorah, potato latkes and some dance parties – it still does proclaim them as Jews and despite the fact that they are “assimilated” they are celebrating their Jewish heritage.
Of course, we are all kind of assimilated, most of us have English names (wasn’t one of the Hellenist things to take on Greek names?) we speak like the locals, mostly look like the locals and have pretty much assimilated into American culture – no matter how much we think we retained our 19th century shtetl culture, that culture was also a by product of that current society, I imagine that in 100 years Jews will see all these Jews from the alte heim wearing baseball caps and that may become the frum thing to do.
Chanukah is one of the easiest holidays, even getting the mitzvah of purim is something most people don’t get, of course how many people are persumay nisa and what exactly does that entail, since the 8 days of oil miracle is only one aspect on the story.
FYI: I am coming last minute to NY for my brothers sheva brachos tomorrow and was interesting in putting on an impromptu show on Saturday night, if you have a space, please get in touch with me – firstname.lastname@example.org and if you want to help me pay for my rent, because I just used that money for my last minute flight send all chanukah gelt to my paypal account.