Bachata
After much deliberation, last February I started going to bachata classes. So far I completed ~10 classes. As someone who has no ear for music, it's quite a hard to learn.
In bachata, guys usually lead the dance. So they need to find the beat and get the ball rolling, so to speak. Even after 10 classes I still struggle to find the beat, and then to get the count correct.
With no muscle memory to help, I feel my brain working at maximum to coordinate the difference aspects of the dance. And I feel the brain fuming after about an hour.
I guess this will be much easier with any kind of prior dancing experience, or with a ear for music. So far it's an interesting, and humbling experience for me.