Our shoulders need regular maintenance to release them from stiffness. Off-set the hunched over effect by opening up the shoulders to remain functional and comfortable. I too suffered from stiff shoulders working at a desk. I commonly use eagle arms to actively stretch and open the shoulders. It is also practised by a lot of surfers at our studio. Please note this pose is not comfortable for absolutely everyone so I have included a modification.
Cross the arms and bend the elbows, have the right arm looped under the left to begin with, wrap the palms to meet or clasp the wrist, squeeze the arms towards each other and on an inhale lift the elbows up and exhale while drawing them down.
Wrap the hands behind the back with the elbows facing forward and hover the arms up and down.
Try to encourage the shoulders to slide down the back whilst holding the pose.