This Treadmill Workout Will Probably Be the Most Intense 30 Minutes of Your Day

It didn’t take much convincing to see why Sandra Bullock, Amanda Seyfried, and Kim Kardashian all flock to Barry’s Bootcamp – 15 minutes into my first class, I was in love. The hourlong mix of high-intensity treadmill intervals and circuit training left me a sweaty mess, and I was already planning my next class on…