Simply sitting down provides a comfortable stretch for your chest and shoulders.
By moving your arms, you can perform wide-ranging movements around your chest and shoulder blades, helping to improve flexibility in the upper body, which tends to become stiff.
The chest-opening movements also make this exercise ideal for those concerned about posture issues such as a hunched back or rounded shoulders.

The motion of opening and closing your legs helps improve flexibility around the hip joint, focusing on the inner thighs. It’s also recommended for conditioning those who are concerned about stiffness in the hip joint or difficulty moving their legs.

While seated, twist your core to stretch your lower back.
This movement—twisting your upper body from side to side—helps improve flexibility in your lower back and core. It’s recommended for those concerned about stiffness caused by long hours of desk work, as well as for conditioning exercises that focus on lower back mobility.