a rod for (one's) (own) back

Future problems caused by something ill-advised that one is doing in the present. Primarily heard in UK. I'm telling you, if you don't get some more exercise now, you'll be making a rod for own back when you get older. These reckless investments a going to turn into a rod for their backs down the line. I try to keep the kids from exclusively eating junk food because I don't want them making rods for their own backs when they're too young to know better.