Are you bored? Try one (or all!) Of the following workouts to pay attention to your core muscles. Each workout is filled with different moves that keep your routine fresh and work your core well.
Includes: Lateral Lunge, Push-up to T, Knee-Lifting, Arm-Leg Transfer, Hunched Over Row and Turn, Knee Crunches, Oblique Stretch, Side Kink
Read the full training here.
6 Core Moves Better Than Crunches
Includes: Plant Pull Thru, Windmill, TRX Tuck, Lo-Hi Hoe, TRX Roll-Out, Plank with Leg Raise  Read the complete workout here. 
Core and Flexibility Training
Includes: Squat Strike, One-Leg Anterior Bridge, Twist, Dead Beetle, Buttocks Extension, Gap Bridge, Alternate Superman, Scorpion Extension, Lower Back Extension, Thigh Extension, Hip Flexor Stretch, quadriceps stretch, IT band stretch
Read the entire training here.