If you sometimes feel that way you are a high achiever, as true impostors do not feel that way but everyone who truly is doing great things feels that way. This little but not well known piece of psychology is quite important for many in our line of work. The reason is that it is not considered a mental illness, just an affliction, but one that I have seen creates a lot of problems. Usually hard workers put in a lot of time to get good results. Often this leads to them being praised and in their mind they commit themselves to even harder work to avoid being found out as a fraud. The real bad effect is that it destroys families and leads to bad health.
Other symptoms are that most high achiever are very good in using charm and the right fashionable words when talking with others. This however emphasis the feeling of being ‘phony’ and being an impostor and usually leads to even more insecurity. Another additional problem arrises when others ask for a measurement of the work of the high achiever. The high high achiever will then usually do everything to avoid being measured as he fears to be found out, just pushing him or her (as this applies evenly to men and women) even deeper into the impostor illusion.
For all this it is very important to always remember that true impostors never fell that way, which is a reason that they are often not found out and if they are discovered then usually by serendipity. When you are affected by this one of the best ways to get rid of it is to write down all the feelings of being a fraud and then to analyse them later, preferable with someone very trustworthy. This is actually one of the few things helping as the infliction is often put aside by others and as a high achiever you are also likely to see most professionals in psychology as impostors themselves.