Sidebends balance the body in that they lengthen the abdominal muscles, hips and (lateral) thighs. The ribcage is opened up because sidebends release the intercostal muscles. This is very beneficial for breathing, in general. They also improve spinal flexibility. They also help to relieve respiratory conditions, such as asthma, allergies, and colds. Good for the smaller intervertebral muscles that stabilize the spine during various movements Good for releasing the (outer) Hip joint.
Minimal movement or static sitting throughout the course of the day dials in the position of the body musculature. The muscles get locked into a position which becomes more difficult to release over time. Particularly, the sitting position facilitates shortening of the intercostal musculatures. shortening of these muscles inhibits full expansion of the chest and, by extension, full contraction of the diaphragm. Breathing is compromised to a large degree. Thus, movement and releasing are necessary to circumvent this occurrence.
The spine moves in six directions. Two movements, left and right lateral extension will be discussed here. Addressing complete, multi-directional spinal movement helps in sustaining spinal health. Movement must be employed in the quest to maintain spinal health. Lateral flexion is bending the body to the right or left side. It helps to open up the side-body, strengthens the obliques, and is helpful in increasing flexibility of the spine. Lateral flexion also opens up the ribcage, helping to expand the lungs and aid in deeper breathing.
Additionally, side bends aid in lengthening the abdominal muscles. this creates space for the digestive organs. They lengthen the muscles of the outer thighs and hips. This aids and regulates digestion, elimination, and metabolism. Expectant mothers can also benefit from gentle side stretches, which will help to create more space in the torso for the organs and the growing baby.
Examples of lateral flexion in yoga: Standing Crescent pose, Parighasana (Gate pose), Parivrtta Janu Sirsasana (Revolved Head-to-Knee pose).
Take a moment, stand up, bend to the side, breath.
Ab-Sutra Wellness and Fitness 
That chair stretch looks like it feels great!