Setu Bandha Sarvangasana (Bridge) & Wheel (Urdva Dhanurasana)

These are two great back extension poses. When in these positions, think of your heart opening as your chest opens up to the sky. Start with Bridge pose as it's an easier pose. As you get more comfortable with bridge, you can slowly progress to Wheel Pose. 

Neither of these positions should be painful. These positions should feel comfortable. I recommend doing a warm up before you do these positions, as to ensure that your body is ready for this back extension stretch.