There is something about hordes of people dancing. There’s something even better about hordes of people you have seen dance before all dance to the same song, even though they’ve been in different movies across different centuries!
This clip starts slow – if you’re in a hurry for motivation, skip to about 1:00 minute.
And for follow up, here’s another which features television and flash mobs mixed in with movies.
And finally lots of Fred Astaire and his contemporaries with a bit of Grease thrown in