Stress and aviation do not match. I have always reminded my students to leave their personal lives outside once they are ready to step into the cockpit. If, for some reason, this is not a possibility, then the flight should happen another day. Stress and living organisms go hand in hand. It is unavoidable. The point here is if it is manageable or not. Every human has a personal tolerance, and a personal way to cope with stress. Teach your students about the topic, and encourage and guide them to learn about their own limitations.