If your reaction is not a reflex developed in training, it is not yours. Flying survival often requires that you react contrary to instinctual responses. Know what to do, believe that it will work, do it. An emergency will always be a surprise but what you do MUST be thought out ahead of time and planned to achieve the safest results. Timely thinking reduces time needed for thinking when there is no time.
Emergencies have similarities of occurrence and procedures.
In most cases a landing is going to be required. The POH usually mentions this. There are several typical solutions to emergencies. Undo what you did. The new revision of the Flight Training Handbook lists eight 'emergencies'.