Sometimes it doesn't take much effort. Sometimes it takes a lot. Depends on what values and desires are in conflict, what everyone else is doing, how likely you think you are to get caught (not getting caught would of course bring in a different desire into the question), and probably some other values/desires that I can't think of now. Many people set their life up so that they avoid the conflicts they believe would be a problem for them.

People are complex creatures with complex values and desires. Sometimes two values are in conflict (which may be a hypothetical or real situation) so it is impossible to be true to both values at the same time.