Oh hey, it's Nina Dobrev, featured in the hardest HIIT workout I've ever done. Seriously — I've followed this video at least five times now, and I still can't complete every circuit. The hardest interval alternates push-ups and burpees; you do two of each, then four, then six, all the way up to 10. And then back down. Good thing the soundtrack is on point, because you're going to feel the burn everywhere.