What is it? Are you living true to yourself? I find it a confusing concept - we are all flawed in our own way, and while we can but hope to change ourselves a little and be aware of our behaviour that is "flawed" sometimes we still offend people we didn't mean to offend. Worse - that some people just don't like the "real" us.
Quite a few people mentioned this article to me over the weekend - either that it resonated with them, or they passed it on to someone who they felt could do with some encouragement in that regard. (If you can't read it, click on it for a bigger version).
Whatever it is, I think it's something that requires constant reassessment - we are always changing.