Consider standing up at the computer, try not to it for longer than 30 minutes at a time. Interact with your colleagues (if appropriate) to ask questions instead of using email. Stretch your body out regularly. You will feel more relaxed for doing it. Rotate shoulders, Twist from side to side, Stretch your arms out in front, hold arms out to sides, Gently push your palms together, fingers pointing upwards, repeat palm push with fingers pointing downwards.