The imposter syndrome

Ever heard of imposter syndrome  psychological state? Probably yes, but most probably not. Literally it's, "a psychological pattern in which one doubts one's accomplishments and has a persistent internalized fear of being exposed as a "fraud". Despite external evidence of their competence, those experiencing this phenomenon remain convinced that they are frauds and do not deserve all they have achieved. Individuals with impostorism incorrectly attribute their success to luck, or interpret it as a result of deceiving others into thinking they are more inteligent than they perceive themselves to be."  Wikipedia.

It's definitely a negative self-perception that arises as a
result of poor self-esteem and or poor self image. 
So the best way to go about it is to start by changing
how you see and talk to yourself.