one's own worst enemy

(one's) own worst enemy

Causing complications to one's life or keeping oneself from success; self-destructive or self-sabotaging. Tommy's becoming his own worst enemy with the way he's been skipping school lately. She always sabotages a relationship when it's going really well because she's her own worst enemy.
See also: enemy, own, worst
Farlex Dictionary of Idioms.

*one's own worst enemy

Fig. consistently causing oneself to fail; more harmful to oneself than other people are. (*Typically: be ~; become ~.) Ellen: My boss is my enemy. She never says anything good about me. Jane: Ellen, you're your own worst enemy. If you did your job responsibly, your boss would be nicer.
See also: enemy, own, worst
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • (one's) own worst enemy
  • your own worst enemy
  • every man is his own worst enemy
  • be (one's) own worst enemy
  • be your own worst enemy
  • walk heavy
  • like to hear (oneself) talk
  • like to hear oneself talk
  • stay hungry
  • too big for one's britches (breeches)
References in periodicals archive
One's ego is often one's own worst enemy! Just because you once hit a seven iron 175 yards doesn't mean you always hit it that far.It is very sensible to take one, two or three extra clubs to ensure that your ball goes the correct distance.