Ensure your chair is adequate to support your back and allow you to sit against the backrest to gain optimal support to the spine. You may find leaning against a cushion or a rolled-up towel will help. Keep your shoulders relaxed and position your screen and keyboard directly in front of you, to prevent unnecessary twisting. Adjust the height of your chair to keep your knees level with your pelvis and your feet flat on the floor. You can sit on a cushion or place something under your feet.