In our daily course of actions, we tend to do many things which we know are not good. The are bad in terms of of the negative affect they have on a living being (including ourselves). And what would we call a negative affect, abstract nouns like pain, hurt, etc. So, we know some of the actions lead to negative affect, still end up doing the same at-times! Only knowing is not maturity, but implementation is what counts.
So always aim at doing not, what you know not to do!