Honey… the only way anyone could consider working in retail easy is if they like the idea of being overworked, underpaid, undervalued, and forced to eat crappy food from food courts. Blech. (I did retail for years and it was a nightmare.)
Depending on if you have resources available, if you can leave your store for a break, go for a run, run up and down a few flights of stairs.
Otherwise, I would suggest finding a HIIT workout you can do at home. Most of them can be done in as little as 10 minutes (ever checked out a ZWOW?) That way you can get your workout in without having to dread the time it takes to get it done.