My favorite response to “How are you?” comes from a Russian former coworker: “Average. Worse than yesterday, better than tomorrow”.

I heard this phrase described as "Russian Optimism".

American here:

I did it last night with a cashier and she laughed and was, I think, amused by the novel response. It seemed to brighten her up a small amount. She then continued to make conversation by saying “Well let’s see if we can’t get you to better than normal.” That was slightly offputting and I wish she didn’t feel the need to take it there. I’m perfectly content with feeling “normal”.

I suppose the way I think of it is like dynamic range of expression. Normal is baseline and perfectly suitable. It’s where I like being. Great or bad are for special cases where I feel extraordinary.

My go to answer is, "can't complain". Vague enough to leave it alone if the question is trivial, but also open-ended enough to expound upon if the other person is genuinely interested in my well-being.

Reminds me of the old joke:

-- What, "can't complain"? Really? You're in a Siberian prison camp, starving and freezing your toes and fingers off, and you "can't complain"?

-- Yes, when you're in a Siberian prison camp, you can't complain...

Me, too. It's a very Midwestern response... [0]

[0]: https://youtu.be/vm-MrkoJPC8?t=35

I also like "hangin' in there" -- especially since Covid started.