I just found the "FB Behind the Scenes" playlist on youtube again and...

This is so me during HIIT: https://www.youtube.com/watch?v=KHqhqMGbsH4

Here is the whole playlist: https://www.youtube.com/playlist?list=PL5lPziO_t_VgD8aOAaw8kNHmrXvYU2AlR

Smile guaranteed after maximum 10 seconds, I daresay :)

Thanks K&D for sharing!