Halloween ("Hallowed Evening") was a pagan Celtic tradition from the 7th century, when it was believed that the boundary between the land of the living and the spirits was very thin, allowing more interaction between the two. Adopted by Christianity and exported to the US and other places...and then commercialised.
Just got back from a 6km march with my dogs.
Here's one of the songs on my exercise playlist.
I like this type of music because of its quick and consistent beat.