Working retail while pregnant: BAD IDEA

I was recently hired as a manager at a clothing store. I was previously working in a call center. This may have been the worst decision I've made so far lol. My feet hurt so bad. And I never thought moving maniquinns and fixtures around would tire me out so quickly! I'm just about 18 weeks and idk if I'll make it to 40 weeks with this job. You'd think it was easy work but my body aches terribly. Anybody coping with working on your feet full time? Please tell me how you do it!