be your own worst enemy

be (one's) own worst enemy

To do things that complicate one's life and/or keep one from success; to be self-destructive or self-sabotaging. Of course Tommy started skipping school again—he's his own worst enemy. 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.

be your own worst enemy

act contrary to your own interests; be self-destructive.
1993 Richard Lowe & William Shaw Travellers We convinced ourselves that everything was against us but the truth was we were probably our own worst enemies.
See also: enemy, own, worst
Farlex Partner Idioms Dictionary

be your ˌown worst ˈenemy

be a person who often creates problems or difficulties for himself/herself: He spends all his money on clothes, and then finds that he’s got nothing left to live on — if you ask me, he’s his own worst enemy.
See also: enemy, own, worst
Farlex Partner Idioms Dictionary
See also:
  • be (one's) own worst enemy
  • (one's) own worst enemy
  • one's own worst enemy
  • your own worst enemy
  • every man is his own worst enemy
  • like to hear (oneself) talk
  • like to hear oneself talk
  • no person is free who is not master of himself
  • marry above oneself
  • above (oneself)
References in periodicals archive
YOU could be your own worst enemy if you always feel a formal invitation is needed to visit your family.
Dr Miriam: They party without us
But you can be your own worst enemy when there's a lot of negative chatter going on inside your head.
Split decision: when your best bud sends you a postcard from Splitsville ..