In a practical view of the world, what does it mean when we feel we done something "wrong"? What is the sense of "shame", "remorse", etc. that we feel after it? Are these concepts solely based on a "romantic" view of the world?
Even more depressing is the concept of "will" power ...
When we feel conflicted over repeating a "bad" habit, a lot of times, the conflict is between our short-term and long-term desires and benefits.
I cannot think coherently!
A common theme seems to be (self-imposed) "boundaries".
There are useful habits, in the sense that they help us in dealing with difficult situations and decisions in life. Harmful habits, on the other hand, typically help us deal with some problems but potentially cause more serious problems. Labeling harmful behaviors as "sin" adds a layer of complexity to the issue. It motivates us to avoid them. In this sense "moral" values add a rigidity to the boundaries, that may be useful.