This fat burning no equipment HIIT routine focuses on the lower body to help lean out your legs, trim your thighs, and sculpt your butt. Each exercise will be 45 seconds with a rest period of 15 seconds in between. You’ll do 4 rounds of exercises with a different focus each time, but it’s all about the lower body here. You’ll start with a warm up to get your body ready, then finish off with a nice stretch to recharge and relax.