Some asanas are made to open your upper body and strengthen your base (your hips and your lower back) Finding a supportive and strong base your upper body becomes buoyant┬á and free as you discover the extension in your spine and the great openning of your heart.
As your body becomes more flexible there is a tendency that your emotions and personality become more flexible as well. Helping to have a friendly and “easy going” behavior. When you do asanas to open your chest/heart you are working to be more gentle, kind and lovely with yourself and others, you also expand your ability to access the graceful freedom.
Working on bending the torso backwards as: bhujangasanas (any variation), kapodasanas, ushtrasanas: they are all asanas to open your chest and build a strong back.
To compensate: bend the torso forward: paschimottanasanas.
P.S. Avoid these exercises (bending backwards) if you have back pain!