So, you're a sapient, fun loving, and incredibly bored horse and so are your millions of culturally similar hoofed amigos. What sports could sate your equine needs?
To specify this is aside from the obvious Equestrian sports already enjoyed ,or more likely not, by real world horses and by no means has to be a human sport, and alongside this, this isn't just a question of possibility but if it would be enjoyable. Eg; Would a horse enjoy bowling? Paragliding? Bobsled?