As with assignments, this is the phase when you actually do the task - sit the exam or produce the final version of your end-of-course assessment. This is where monitoring your performance is really important. For most students, the crucial thing in an exam is usually to monitor the timing. Unlike the production of an assignment, an exam is a timed test; so, you need to pace yourself appropriately. Most end-of-course assessments have no time constraints although you may find the deadline very tight. Again, monitor your performance carefully. But timing is not the only thing to monitor - check that you are answering the question asked; that your calculations are accurate, and so on.
You may remember that the second component of the implementing phase was to make a self-assessment. This may sound a strange thing to suggest in relation to exams. However, generally students do not get many opportunities to improve their performance in exams so, once the actual event is over, make yourself spend a short time trying to assess your performance before the details fade in your memory.