Sanctity includes seriousness.
Seriousness is giving everything its correct importance and reaction.
This means objectiveness.
Objectiveness means to have a maximum goal, which should be the greater glory of God.
That means everything is ordained in relation to that.
You take a bath because you must be clean, because it is not only a sign of interior purity, but also neccesary for an agreable life with others and yourself.
But even with this mind set, this is in the end a prosaic act. All prosaic acts should be done with in the most quick and efficient manner as to but your mind on other things. Another thing is listening to a conference while you shower, another is stoping to read.
Plus, my first thing is that siting on a tub even with a good book is only a step if not sloth already, and the Devil takes advantage to tempt with impurity.