Back pain - new job

I start a new job here soon and I’m terrified I won’t be able to handle it due to the amount of standing & heavy lifting , but I have to keep it .

I’ll be standing for about 10 hours a day, with two 15 min breaks and a lunch .

I start in a week, is there anything I can do to help strengthen my back beforehand ?

I’ve worked a desk job most of my life , so im pretty out of shape . I can stand at the kitchen sink doing dishes for 15 minutes and my back starts pinching really bad, and I have to start rocking side to side to minimize the pain, and eventually sit down. 🙄