Just like Anatta, equanimity is the tough one. I can see anger and inpermanence but not self is a bugger. Metta, karuna and mudita fine and good but Upekkha thats another tough one. Lets see whar Access to Insight tells us
Equanimity is a perfect, unshakable balance of mind, rooted in insight.
Looking at the world around us, and looking into our own heart, we see clearly how difficult it is to attain and maintain balance of mind.