One Reason I don't Like Working at Grocery Store

Obviously I have a very long list of reasons that I don't like working at the grocery store.  One of the biggest reasons is because it requires 0 brain power on my part.  I noticed today that I hardly pay attention to what I'm doing while greeting the customers, scanning/bagging the groceries, and cashing out the customers.  I was zoned out during most of the shift.  It didn't help that I was ridiculously tired.  However, although I hardly paid attention to what I was doing, I still got the customers out quickly.  I scan and cash them out very fast.  I have been doing it for well over 9 years.  I can do the simple math in my head most of the time.  Obviously when I put the numbers in the register, it tells me how much change to give.  Some cashiers have to think about how to add the change up and give it to the customers, though.  I enjoy jobs with a challenge.  I like thinking and learning in a job.  This job doesn't do it for me.  That's why I really don't like it, but money is money and that's what I need!