Stress on evening shift!

So I work on a busy surgical unit. We are not med-surg. We see strictly GI, urology, vascular, plastics, trauma etc. I work an odd shift 2p-11:30p. This shift exists because we get a lot of post-ops from 2pm-on. It's normal for me to have 1-2 patients on the floor, plus 2-3 postops that I will take from PACU. It's the busiest shift on the unit, day and night shifters agree.

I've been managing it well, my time management has improved ten-fold.

My issue is BEFORE I go to work. I am up by 9am, and spend my whole morning until 1pm dreading going to work. It puts me in a funky mood and my boyfriend can tell, sometimes I feel like I even take it out on him. Part of it is that we also float to other units kind of often and I DREADDDD that possibility.

Does anyone have any good methods to help me overcome this and to improve my outlook on the impending shift?

Currently, we wake up and eat breakfast together. Most days we will take a 30 minute walk through the neighborhood, come back and eat lunch/shower. But I still between all that find a way to be a grump about work. Would a more vigorous workout help me?