Stretching keeps muscles flexible, strong, and healthy, allowing us a full range of motion. Too much sitting can cause muscles to shorten and become tight, so stretching can help to compensate for this.
As well as increasing your flexibility, stretching also increases blood flow to your muscles, can help improve posture, are great for stress relief, and can encourage the body to release tension.
If you stretch correctly and regularly, you will find that every move you make becomes easier. In yoga we bend so we do not break!