If you fall into cold water what is the first thing your should do until the cold shock response lessens?

If you fall into cold water, the first thing you should do is to control your breathing and avoid hyperventilation. Focus on taking slow, deep breaths to calm your body and manage the cold shock response. Try to keep your head above water and, if possible, orient your body to minimize heat loss while you wait for the initial shock to subside. If you're unable to get out of the water immediately, attempt to stay as still as possible to conserve energy and retain body heat.