make a rod for your own back
make a rod for (one's) own back
To cause problems for oneself in the future by doing something in the present that is ill advised. Primarily heard in UK. I'm telling you, if you don't get some more exercise now, you'll be making a rod for yourself when you get older.
make a rod for your own backBRITISH
If you make a rod for your own back, you do something which will cause you many problems in the future. You're making a rod for your own back, you know, letting the child into your bed at night. You'll never get her to stay in her own bed now. Note: Verbs such as create are sometimes used instead of make. In a way, the company's success has created a rod for its own back, for the style is copied everywhere. Note: This expression refers to someone providing the stick with which they themselves will be beaten.