Equanimity is one of the words I very rarely use.
The reason is the same as for some of the other “spiritual” words I rarely use: It’s so often misunderstood. It often comes with unfortunate associations.
The “myth” of equanimity is that it’s a state free of sadness, anger, grief, joy, exhilaration and so on. It’s some sort of tranquil state, which – in a way – looks more like numbness. It’s one of the “dreams of the ego”, a dreamy wish to be free of the ups and downs of life. The ups & downs which are painful when they are seen as “other” and a problem. (And that wish comes from a wish to protect the imagined self, it comes from love.)
For me, equanimity is more of a sense of ease through these natural ups & downs inherent in life. It’s an allowing of the experience that’s here, as it is.
In a sense, it’s a shift of “center of gravity” from the parts of us that wants our experience to be a certain way, to the “part” of us that already allows it as is – welcomes it as is, is it as is. (Which is not really a part of us, it’s that which allows and is all parts.)
And more importantly, what’s alive here now? How is it to welcome and allow what’s here?