It's a tough one. Readers sometimes point out your faults. This is a difficult thing to deal with unless you are a supremely confident person. But, we are all hypocrites here maybe, because I've certainly been gripped with a fierce urge to wield the red pen when reading other people's work.
This is where a professional editor is invaluable. It's a bit like learning to drive - you take the criticism when it comes from a professional. It's a lot more difficult when it comes from family/friends.
I've mentioned before just how much my writing has benefited from my editor, Sharon's input. I was quite oblivious, in particular, of my overuse of particular phrases and words..."really," "a bit," "obviously." These were littered throughout my work. If you think about it, they are all qualifying words - all designed to dilute what I'm trying to say! All possibly denoting a confidence issue.