What are the negative effects of routines?

You probably will have noticed that, in the case of habits and routines, our attention is glued to the positives and not much is said about the negatives. Perhaps it is time we changed that. Yet discussing something as important as how to lead our lives needs to be a balanced approach, one that highlights the benefits as well as the downsides of any so-called ‘key to success’. We should also be clear about the quantity of routines and habits we are talking about: is it a matter of introducing one or two new habits, or something more like having one’s entire life be mostly routine-based? Obviously, whichever option we have in mind will significantly impact whatever downsides.