OK, so you have determined there is one aspect of your life that you do not have control over. Lack of control is highly stressful. But don't fixate on that. What are the areas of your life that you do have some control of? How much free time do you have each day? Is there any skill or hobby you could take up during your free time that might make you feel less like these next couple years are a complete waste? Can you practice mindfulness (focus on the feelings of your body and the immediate information coming in from your five senses, pay attention only to the task at hand, note distracting thoughts and move on without pursuing them, if a worry about the past or future comes up simply notice it without judgement and return to the present moment, etc) while you are on duty so as to reduce the distress that it causes?
I successfully follow this advice only about 10% of the time but even that is something...