One should be on one's toes and alert of one's surroundings if malicious people are around, to ensure that they cannot wreak havoc in one's life.

(idiomatic) To insist on the total realization of a goal and reject any compromise, thereby decreasing the chance of achieving even a part of that goal.

(intransitive) To reject or bar improvement because it is incomplete.

(idiomatic) After a plan against an enemy is drafted, there will be unexpected elements from the opposition that will call for improvisation.

(US, law enforcement, dated) A person who ranks highest on the federal government's prioritized list of wanted criminal fugitives.

(idiomatic) To cause problems for one's self, act contrary to one's own interest, self-sabotage.

Third-person singular simple present indicative form of be one's own worst enemy

simple past tense of be one's own worst enemy

Alternative form of perfect is the enemy of good

past participle of be one's own worst enemy