kill (one)self
1. To commit suicide. Once John realized he had begun to have thoughts of killing himself, he decided to seek help.
2. To bring about one's death by performing a particular action. This phrase can be said when one's life is or could be in danger, but it is often used figuratively. I can hardly breathe—I'm going to kill myself if I go back on the treadmill right now! If they try driving home in this snow, they'll kill themselves—tell them to get a hotel room for the night.
3. To overexert oneself. Don't kill yourself trying to get the report done tonight—it's not due until next week anyway.