Does anyone else have a physically demanding job?

Celeste • Pregnant with baby #1 EDD April 3rd, 2016!
I work as a nurse doing 12 hour shifts 3 days a week. My plan is to work up until a week before my due date (I am due April 3rd), but I am already having  more and more difficulty getting through my shifts due to being so exhausted. Any other mommies in the same boat? And if so how are you handeling things?