Wordology

If something is run of the mill, it is average, ordinary, not special. It most likely originally referred to a run from a textile mill. It is material that has been manufactured, before it is decorated or embellished.

The expression you have your work cut out for you comes from tailoring. To do a big sewing job, all the pieces of fabric are cut out before they get sewn together. It seems like if your work has been cut for you, it should make job easier, but we do not use the expression that way. It is more that the task is ready to be tackled, but the difficult part is laying out the pieces in order, and doing the actual sewing.