Appearances can be deceiving, the mind is much more fluid than people believe! In psychology writings, the subject of lying is one of the most fascinating things. I would say at least half of what everybody tells you is a lie, to some degree. Even many of the most important childhood memories you have are lies that you reconstructed later on based on experiences related to you later, although when you relate them, you are not consciously lying because you yourself believe that it happened as you "remember".
Listen, if you did not lie everyday of your life you would not survive in this world. Everybody with no exception lies all the time, some people are just so deluded they believe they are honest all the time. Not all lies are exactly the same of course, some are deliberately, consciously forumulated with the intent to harm. Problems actually arise for you in everday life when you are not good at lying, or another way of saying it is that when you are too consciously aware or troubled by your own lies. Or if you tell lies without a good system for covering them up (or unbelievable lies) or dealing with the fallout when exposed. Mentally healthy people lie with such ease that they do not even consciously admit to themselves that they just lied about certain things and are adept at explaining those lies away, yet there are other things they will not lie about. Sometimes we knowlingly create lies and repeat them so often that we believe them, and even later change our behavior in an attempt to make reality conform to our belief and avoid cognitive dissonance. Never underestimate the power of denial.
Different cultures (and subcultures) have different usually unwritten and rarely spoken standards about what it is absolutely not okay to lie about, and what it is okay or required to lie about. Usually the lies of others are easily discerned, but it's important for our own well-being that we not focus too much on those of our selves or our own group.
If you tell lies that are too big for you to maintain or too frequently though, your anxiety increases. Genrally, this can be reduced by being a part of a group of people who accept more of what you do, thus reducing the need to lie as much and your "transaction cost" of keeping up the facade causing a dissonance between what you are doing and what people around you think you should be doing. Relationships with other people will discourage you from lying about what those particular people do not lie about, and encourage you to lie about what they do lie about. It creates an external reference point of belief and behavior, an internal structure of mind, an identity.
If you stop having any relationships with any people you value for whatever reason, or if you think extremely indpendently, then you have no healthy reinforcement of the acceptableness of the lies you do tell. You are then what they call a sociopath, and possibly a psychopath...if you truly form your own opinions without concern for what others will think. If you are not skilled at lying about what a particular group or person expects you to lie about in certain situations, you will be rejected.