3 Flat-Ab Exercises From Shaun T — and All You Need Is a Chair

• Sitting with your spine straight and tall, kick your right leg forward, flexing through your heel while punching with your left arm. Pull your right elbow back to engage your back.
• Then switch sides. Both legs will be in the air for a moment, which will make your abs work harder.
• Every time you kick your legs, pull your abs deeper toward your spine.
• Continue for a minute, doing 30 seconds fast followed by 30 seconds slow.

Shaun's note: You might feel a burn in your hip flexors, but they need to get strong with the abs.