dig (oneself) an early grave

To do things or act in a way that is likely to result in one's premature death. You're going to dig yourself an early grave if you keep drinking as much as you do now. John's such a workaholic that I worry he's going dig himself an early grave. A: "I can't go to bed, I have too much to do!" B: "Fine, go ahead, dig yourself an early grave."