The 30-Day Shred is made up of three different levels, all following what has been repeated over and over as “Jillian’s typical circuit training.” That means that you complete three circuits in one workout, each circuit with different exercises. And personal trainer Jillian. Michaels has managed to turn her Biggest Loser gig into a fitness empire. When she’s. Tie-ins like The Biggest Loser Challenge bring celebrity trainers into your living…