YOU are your own worst enemy.

你是你自己最大的敌人。

youdao

Unfortunately, I was my own worst enemy.

不幸的是，最大的敌人是我自己。

youdao

We fear that we are our own worst enemy now.

我们很害怕，害怕最大的敌人就是我们自己。

youdao

Because smart women (in their youth, bright girls) are often their own worst enemy.

FORBES: Bright Girls, Smart Women: Often Their Own Worst Enemies

In other words, the PTO is forcing the patent owner to become his own worst enemy.

FORBES: New Patent Regs May Inspire More Litigation, Not Less

Indiana has become its own worst enemy, producing more stars than its flagship school can retain.

WSJ: Indiana vs. Michigan: Indiana Faces Off Against...Indiana