There's a reason parents will give a knowing smile when people without kids, or parents-to-be, say they'll "never" do something. 

And maybe you won't.  You'll have rules and routines and will stick to your convictions.  And then one day you'll find yourself in a new place, on vacation, and routines will go out the window.  It will be late and everyone is tired and crying.  You'll be at the end of your rope and you'll think...well maybe...