It may seem silly, but do sets of push-ups, sit-ups, chin-ups if you have a bar, or something
secure to hang on to. If you're sure there's not gonna be a rush, run around your store a
couple of times (outside of it, you'd look really silly doing it inside.)
I know it's not really the same, but when me and my friend worked a concession stand at
Fairs, we'd have one person stay behind during slow times, and the other would go out
for like 30 minutes (working 12 hours a day at not-very popular fairs, you had ALOT of slow time.)
Try something like this with a buddy-co-worker or something. If both
of you could get into it, I'm sure it'd be easier to get your exercise.
