I can remember a conversation that I had with a Zen Master some years ago. I was complaining to him about the voice that would speak to me in my head - you know the one - the one that has really unhelpful, self-denigrating comments to keep you from believing in yourself and sparking all kinds of self-doubt. He responded by saying, "Just ONE!? You are so lucky! I have at least 1000 voices like that!" We had a little laugh and then we spoke about this on a more serious level, investigating the possible nature of these "voices".
To be honest, I can't really remember our conversation after that, but I can tell you that I have thought about this topic quite frequently. Not only looking at my own, but working with clients as they discover these unhelpful voices in their own head. These voices may be the product of our early conditioning, specific past events, both verbal or non-verbal communication from significant people in our pasts....but what seems more important to me, is to see them when they arise and to question their validity and usefulness.
Maybe the voice is saying something like, "You never do anything right!" Write it down. Look at those words. Is it true? It's doubtful that you NEVER do anything right. And to get a little bit pickier still, what does 'RIGHT' mean anyway? According to whom exactly? Our parents? Society? The neighbors?
I'm not saying that we shouldn't have expectations or ideals or goals to help us measure where we are at - that can be helpful. What I am saying, is that we may want to be curious about these negative comments and see if there is actually any truth to them instead of believing and following them blindly. It reminds me of a bumper sticker that I saw once that said, "You don't have to believe everything that you think."
These voices can be about body image, academic achievements, financial status, relationship issues, to name just a few. We don't need to make war with these thoughts, but some healthy curiosity can go a long way in allowing ourselves to decide if this is a thought that is only serving as a stumbling block to keep us further away from connecting with our deeper self and our world.