I think one of the most interesting dynamics in self improvement are these tiny little walls. I started doing HIITs irregularly over the years because they’re great to do in a small amount of space anywhere. And since I travel a lot, this is a good thing.

But it’s not so good when you’re in a room with thin walls/floors and you’re above someone else. The courteous urge comes up - after all I hate it when someone’s jumping up and down above me, why would I do that to someone else?

This guy has managed to come up with a HIIT series that gets around that - it’s still intense, but it’s a quiet. Brilliant!