How can I reduce back, neck and wrist pain from computer, typing and desk work?

Stretch and Movement. Use good posture/ ergonomics when sitting at the desk performing work related activities. Regularly move your neck, shoulders, back and limbs through various positions as a quick range of motion exercise. Occasional stretches of the muscles in these areas will keep them from becoming too tense which can lead to pain.
Ergonomics. We are not designed to sit at a desk all day. But proper ergonomics of your work station can help. Location of monitor, keyboard and mouse should be at comfortable levels. Regular breaks to allow for muscle recovery and position changes are helpful. Appropriate stretches and exercises are also important.