Slowly and gently pull down on the fingers of one hand with the fingers of the other, to stretch your wrist in the direction opposite from that of mousing. Hold for a count of 25. Now do the other wrist.
Hand and wrist exercises
Use the strength of one arm to slowly and gently pull the other shoulder toward the midpoint of your torso. Hold for a count of 25. Now do the other arm. This helps relax your shoulders, arms, and mid-back.
Put your arms out in front of you; put the back of your wrists together, and slowly and gently stretch your hands away from each other. Hold for a count of 25. This helps stretch and relax your forearm and elbow muscles.
With one thumb, slowly and gently pull the other thumb away from the other fingers of its hand, to stretch and relax your hand muscles. Hold for a count of 25.
Additional hand exercises
Pretend to play an imaginary piano. Now turn your hands over and pretend to play an imaginary upside-down piano. This helps release tension in your fingers.
Keep your ring finger and pinky together, but separate your middle finger from your ring finger. Repeat this motion five or ten times. This also helps release tension in your fingers.
Same idea, different fingers: keep your middle and ring fingers together, and separate your pinky and index finger from them. (This is harder.) Repeat this motion five to 10 times. This also helps release tension in your fingers.
Slowly and gently roll your head forward. Hold for three seconds. Do it three times.
Slowly and gently pull your head straight back, keeping your face level. Hold for three seconds. Do it three times.
Slowly and gently look to the left as far as you can. Hold for three seconds. Do it three times.
Do the same while looking to the right.
Slowly and gently tilt your head to the left as far as you can. (Keep your shoulder down, but try to reach it with your ear.) Hold for three seconds. Do it three times.
Same, tilting to the right.
*DISCLAIMER: If exercises cause discomfort or pain, stop the exercise and consult with a physician.
References: Occupational Safety and Health Administration, eTools for Computer Workstations.