Who do you have unrealistic expectations of?
Most educators strive to give their students realistic expectations for what they can accomplish. All the while, most educators also hold unrealistic expectations for what they personally can accomplish.
I think the best strategy is to meet in the middle. Give your students slightly unrealistic expectations, and only have slightly unrealistic expectations of yourself. For the students, you have raised the bar and put them closer to their zone of proximal development. For the educators, you have reduced the guilt and stress of impossible expectations.
In other words: treat others like you treat yourself. And vice versa.