It varies from person to person.
Often people look right when they lie
People are often known to lie about their drinking.
Yes, if a lie is repeated frequently enough, people may eventually come to believe it.
What Goebbels said was that if you repeat a lie often enough people believe it, not that 'it becomes the truth'.
[deleted, sorry misread your question]
dreamers often lie--->you dream when you are asleep--->you sleep lying down
People with APDs often lie a lot, but continual lying without other antisocial characteristics is usually a pathological condition of its own. See the link below.
You don't have to cheat to lie to your wife. Some individuals may have come from a dysfunctional family where they had to lie for fear of a beating, while some people lie because they do not feel their lives are as exciting as others so they tend to dramatize what happens in their lives. People that lie are often caught at lying so it would be to your best interest to seek out a good psychologist to find out why you feel the need to lie to your wife.
There are no statistics for how many people lie a year.
It is possible that people may be aware when someone is lying, as there are often signs or cues that can indicate deception.
You've miseheard the proverb. It's actually "Halfthe truth is often a great lie."
Not all girls lie, but most do. Both genders sometimes lie as an attempt to get themselves out of trouble. Some people lie just for fun. Many people lie to make themselves look better. The main reason people lie is to not get caught.